Method and device for transmitting/receiving uplink control information in wireless communication system

ABSTRACT

The present invention relates to a method for a terminal to transmit acknowledgement information including: determining a physical uplink control channel (PUCCH) format and resource, in which the acknowledgement information is transmitted in response to a downlink transmission received in a downlink sub-frame set including M(M≧1) downlink sub-frame; and transmitting the acknowledgement information using the PUCCH format and resource in one uplink sub-frame. Here, more than one serving cells are configured to the terminal, and the more than one serving cells can include one PCell and at least one SCell. The acknowledgement information can be transmitted using a PUCCH format 1a/1b when one physical downlink shared channel (PDSCH) without a corresponding physical downlink control channel (PDCCH) detected, exists only on PCell in the downlink sub-frame set, and a semi-persistent scheduling (SPS) release PDCCH does not exist in the downlink sub-frame set.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Phase of PCT International ApplicationNo. PCT/KR2011/008292 filed on Nov. 2, 2011, which claims priority under35 U.S.C. §119(e) to U.S. Provisional Application No. 61/409,485 filedon Nov. 2, 2010, U.S. Provisional Application No. 61/409,547 filed onNov. 3, 2010, U.S. Provisional Application No. 61/409,994 filed on Nov.4, 2010, U.S. Provisional Application No. 61/410,349 filed on Nov. 5,2010, U.S. Provisional Application No. 61/412,362 filed on Nov. 10,2010, U.S. Provisional Application No. 61/412,794 filed on Nov. 12,2010, U.S. Provisional Application No. 61/450,140 filed on Mar. 8, 2011and U.S. Provisional Application No. 61/481,257 filed on May 2, 2011,all of which are hereby expressly incorporated by reference into thepresent application.

TECHNICAL FIELD

The present invention relates to a radio communication system, and moreparticularly, to a method and apparatus for transmitting and receivinguplink control information.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services such as voice or data services.Generally, a wireless communication system is a multiple access systemcapable of supporting communication with multiple users by sharingavailable system resources (bandwidth, transmission power, etc.).Multiple access systems include, for example, a Code Division MultipleAccess (CDMA) system, a Frequency Division Multiple Access (FDMA)system, a Time Division Multiple Access (TDMA) system, an OrthogonalFrequency Division Multiple Access (OFDMA) system, a Single CarrierFrequency Division Multiple Access (SC-FDMA) system, and a Multi-CarrierFrequency Division Multiple Access (MC-FDMA) system.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method forefficiently transmitting control information in a wireless communicationsystem and an apparatus therefor. Another object of the presentinvention is to provide a channel format and signal processing methodfor efficiently transmitting control information and an apparatustherefor. Still another object of the present invention is to provide amethod for efficiently allocating resources for control informationtransmission.

It will be appreciated by persons skilled in the art that that thetechnical objects that can be achieved through the present invention arenot limited to what has been particularly described hereinabove andother technical objects of the present invention will be more clearlyunderstood from the following detailed description.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting Acknowledgement/Negative Acknowledgement(ACK/NACK) information at a User Equipment (UE) in a wirelesscommunication system, including determining a Physical Uplink ControlChannel (PUCCH) format and resource through which ACK/NACK informationfor downlink transmission in a downlink frame set including M (M≧1)downlink subframes is to be transmitted; and transmitting the ACK/NACKinformation using the PUCCH format and resource in one uplink subframe,wherein more than one serving cell is configured for the UE and the morethan one serving cell includes one Primary Cell (PCell) and at least oneSecondary Cell (SCell), and the ACK/NACK information is transmittedusing a PUCCH format 1a/1b, when one Physical Downlink Shared Channel(PDSCH) in which a corresponding Physical Downlink Control Channel(PDCCH) is not detected is present in the downlink subframe set only onthe PCell and a Semi-Persistent Scheduling (SPS) release PDCCH is notpresent in the downlink subframe set.

In another aspect of the present invention, provided herein is a UserEquipment (UE) for transmitting Acknowledgement/Negative Acknowledgement(ACK/NACK) information in a wireless communication system, including areception module for receiving a downlink signal from a Base Station(BS); a transmission module for transmitting an uplink signal to the BS;and a processor for controlling the UE including the reception moduleand the transmission module, wherein the processor is configured todetermine a Physical Uplink Control Channel (PUCCH) format and resourcethrough which ACK/NACK information for downlink transmission receivedthrough the reception module in a downlink frame set including M (M≧1)downlink subframes is to be transmitted and to transmit the ACK/NACKinformation using the PUCCH format and resource in one uplink subframethrough the transmission module, and wherein more than one serving cellis configured for the UE and the more than one serving cell includes onePrimary Cell (PCell) and at least one Secondary Cell (SCell), and theACK/NACK information is transmitted using a PUCCH format 1a/1b, when onePhysical Downlink Shared Channel (PDSCH) in which a correspondingPhysical Downlink Control Channel (PDCCH) is not detected is present inthe downlink subframe set only on the PCell and a Semi-PersistentScheduling (SPS) release PDCCH is not present in the downlink subframeset.

The following may be commonly applied to the above embodiments of thepresent invention.

A resource index of the PUCCH format 1a/1b may be determined by a valueof a Transmit Power Control (TPC) field of a PDCCH indicating SPSactivation for one PDSCH in which the corresponding PDCCH is notdetected.

The ACK/NACK information may be transmitted by channel selection using aPUCCH format 1b, when M is greater than 1, one PDSCH in which thecorresponding PDCCH is not detected is present in the downlink subframeset only on the PCell, a PDSCH indicated by detection of thecorresponding PDCCH in the downlink subframe set is present in thedownlink subframe set only on the PCell, and a Downlink Assignment Index(DAI) value of the detected PDCCH is 1.

The channel selection may be performed by selecting one PUCCH resourcefrom among A (where A is 2 or 3) PUCCH resources.

The A may be determined based on the number of transport blocks of thedownlink transmission.

One of the A PUCCH resources may be determined by a value of a TPC fieldof a PDCCH indicating SPS activation for the one PDSCH in which thecorresponding PDCCH is not detected, and the other resources of the APUCCH resources may be derived from a Control Channel Element (CCE)index of the detected PDCCH.

A TPC field of a PDCCH with a DAI value being 1 on the PCell mayindicate uplink TPC information, a TPC field of a PDCCH with a DAI valuebeing greater than 1 on the PCell may be used for determination of aresource index of a PUCCH format 3, and a TPC field of a PDCCH on eachof the at least one SCell may be used for determination of the resourceindex of the PUCCH format 3.

The UE may assume that the same PUCCH resource index value istransmitted in all PDCCHs on the PCell and the at least one SCell usedfor determination of the resource index of the PUCCH format 3 in thedownlink subframe set.

The wireless communication system may be a Time Division Duplex (TDD)wireless communication system.

The above overall description and a later detailed description of thepresent invention are purely exemplary and given as an additionaldescription of the present invention determined by the appended claims.

Advantageous Effects

According to the present invention, control information can beefficiently transmitted in a wireless communication system. Further, achannel format and a signal processing method for efficientlytransmitting control information are provided. Furthermore, resourcesfor control information transmission can be efficiently allocated.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a block diagram illustrating constituent elements of a UE anda BS performing the present invention;

FIG. 2 illustrates an exemplary structure of a transmitter in each of aUE and a BS;

FIG. 3 illustrates examples of mapping input symbols to subcarriers inthe frequency domain while satisfying a single-carrier property;

FIGS. 4 to 6 illustrate examples of mapping an input symbol to a singlecarrier by clustered DFT-s-OFDM;

FIG. 7 illustrates a signal processing operation in segmented SC-FDMA;

FIG. 8 illustrates exemplary radio frame structures used in a wirelesscommunication system;

FIG. 9 illustrates an exemplary DL/UL slot structure in a wirelesscommunication system;

FIG. 10 illustrates an exemplary DL subframe structure in a wirelesscommunication system;

FIG. 11 illustrates an exemplary UL subframe structure in a wirelesscommunication system;

FIG. 12 illustrates an example for determining PUCCH resources forACK/NACK;

FIG. 13 illustrates exemplary communication in a single-carriersituation;

FIG. 14 illustrates exemplary communication in a multi-carriersituation;

FIG. 15 explains a concept that one MAC layer manages multiple carriersin a BS;

FIG. 16 explains a concept that one MAC layer manages multiple carriersin a UE;

FIG. 17 explains a concept that a plurality of MAC layers managesmultiple carriers in a BS;

FIG. 18 explains a concept that a plurality of MAC layers managesmultiple carriers in a UE;

FIG. 19 explains another concept that a plurality of MAC layers managesmultiple carriers in a BS;

FIG. 20 explains another concept that a plurality of MAC layers managesmultiple carriers in a UE

FIGS. 21 and 22 illustrate slot level structures of PUCCH formats 1a and1b for ACK/NACK transmission;

FIG. 23 illustrates a scenario of transmitting UCI in a wirelesscommunication system supporting CA;

FIGS. 24 to 27 illustrate a PUCCH format structure for feeding back aplurality of ACK/NACK bits and a signal processing operation therefor;

FIG. 28 is a flowchart illustrating predefined resource allocation forPUCCH resource determination in a PCell-only-receiving case;

FIG. 29 is a flowchart illustrating additional predefined resourceallocation for PUCCH resource determination in a PCell-only-receivingcase;

FIG. 30 is a flowchart illustrating an example of using a DAI field asan ARI for PUCCH resource determination in a PCell-only-receiving case;

FIG. 31 is a flowchart illustrating an example of using a TPC field asan ARI for PUCCH resource determination in a PCell-only-receiving case;

FIG. 32 is a flowchart illustrating another example of using a TPC fieldas an ARI for PUCCH resource determination in a PCell-only-receivingcase;

FIG. 33 is a diagram illustrating an embodiment of using a TPC field foran original purpose or an ARI purpose according to a DAI value on aPCell;

FIG. 34 is a diagram illustrating an example of increasing a DAI valuein ascending order of CC index in a bundling window;

FIG. 35 is a diagram illustrating examples for determining DAI values ina CA TDD system;

FIGS. 36 to 39 illustrate various examples of using DAI fields in CCdomain bundling;

FIG. 40 is a diagram illustrating exemplary time-domain partialbundling;

FIG. 41 is a diagram explaining channel selection using PUCCH format 1bin CC-domain bundling;

FIG. 42 is a diagram explaining channel selection using PUCCH format 3in CC-domain bundling;

FIG. 43 is a diagram illustrating an example of use of a DAI and a TPC;

FIG. 44 is a diagram illustrating another example of use of a DAI and aTPC;

FIG. 45 is a diagram illustrating an example of the present inventionfor use of a TPC field in a PDCCH; and

FIG. 46 is an overall flowchart explaining an ACK/NACK transmissionmethod for various DL transmissions according to an example of thepresent invention.

BEST MODE

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention in apredetermined form. The elements or features may be considered selectiveunless otherwise mentioned. Each element or feature may be practicedwithout being combined with other elements or features. Further, anembodiment of the present invention may be constructed by combiningparts of the elements and/or features. Operation orders described inembodiments of the present invention may be rearranged. Someconstructions of any one embodiment may be included in anotherembodiment and may be replaced with corresponding constructions ofanother embodiment.

In the embodiments of the present invention, a description is given of adata transmission and reception relationship between a Base Station (BS)and a terminal. Here, the BS refers to a terminal node of a networkcommunicating directly with the terminal. In some cases, a specificoperation described as being performed by the BS may be performed by anupper node of the BS.

In other words, it is apparent that, in a network comprised of aplurality of network nodes including the BS, various operationsperformed for communication with a terminal may be performed by the BS,or network nodes other than the BS. The term ‘BS’ may be replaced withterms such as fixed station, Node B, eNode B (eNB), Access Point (AP),etc. Also, in the present document, the term BS may be used as a conceptincluding a cell or a sector. Meanwhile, ‘relay’ may be replaced withterms such as Relay Node (RN), Relay Station (RS), etc. The term‘terminal’ may be replaced with terms such as User Equipment (UE),Mobile Station (MS), Mobile Subscriber Station (MSS), Subscriber Station(SS), etc.

Specific terms disclosed in the present invention are proposed to aid inunderstanding the present invention, and the use of these specific termsmay be changed to another format within the technical scope or spirit ofthe present invention.

In some instances, well-known structures and devices may be omitted inorder to avoid obscuring the concepts of the present invention and theimportant functions of the structures and devices may be shown in blockdiagram form. The same reference numbers will be used throughout thedrawings to refer to the same or like parts.

The embodiments of the present invention can be supported by standarddocuments disclosed in at least one of wireless access systems includingan Institute of Electrical and Electronics Engineers (IEEE) 802 system,a 3^(rd) Generation Partnership Project (3GPP) system, a 3GPP Long TermEvolution (LTE) system, a 3GPP LTE-Advanced (LTE-A) system, and a 3GPP2system. In particular, steps or parts, which are not described toclearly reveal the technical idea of the present invention, in theembodiments of the present invention may be supported by the abovedocuments. All terminology used herein may be supported by theabove-mentioned documents.

The following technique can be used for a variety of radio accesssystems, for example, Code Division Multiple Access (CDMA), FrequencyDivision Multiple Access (FDMA), Time Division Multiple Access (TDMA),Orthogonal Frequency Division Multiple Access (OFDMA), Single CarrierFrequency Division Multiple Access (SC-FDMA), and the like. CDMA may beembodied through radio technology such as Universal Terrestrial RadioAccess (UTRA) or CDMA2000. TDMA may be embodied through radio technologysuch as Global System for Mobile communications (GSM)/General PacketRadio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMAmay be embodied through radio technology such as Institute of Electricaland Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802-20, and Evolved UTRA (E-UTRA). UTRA is a part of the UniversalMobile Telecommunications System (UMTS). 3GPP LTE is a part of EvolvedUMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in downlink andemploys SC-FDMA in uplink. LTE-A is an evolved version of 3GPP LTE.WiMAX can be explained by an IEEE 802.16e (WirelessMAN-OFDMA ReferenceSystem) and an advanced IEEE 802.16m (WirelessMAN-OFDMA AdvancedSystem). For clarity, the following description focuses on the 3GPP LTEand LTE-A systems. However, technical features of the present inventionare not limited thereto.

FIG. 1 is a block diagram illustrating constituent elements of a UE anda BS performing the present invention.

The UE operates as a transmitter on uplink and as a receiver ondownlink. On the contrary, the BS operates as a receiver on uplink andas a transmitter on downlink.

The UE and the BS include antennas 500 a and 500 b for receivinginformation, data, signals, and/or messages, transmitters 100 a and 100b for transmitting messages by controlling the antennas, receivers 300 aand 300 b for receiving messages by controlling the antennas, andmemories 200 a and 200 b for storing various types of informationrelated to communication in a wireless communication system. The UE andthe BS further include processors 400 a and 400 b connectedoperationally to constitute elements of the transmitters, the receivers,and the memories included in the UE or BS, for performing the presentinvention by controlling the constituent elements. The transmitter 100a, the receiver 300 a, the memory 200 a, and the processor 400 a of theUE may be configured as independent components by separate chips or twoor more thereof may be integrated into one chip. The transmitter 100 b,the receiver 300 b, the memory 200 b, and the processor 400 b of the BSmay be configured as independent components by separate chips or two ormore thereof may be integrated into one chip. The transmitter and thereceiver may be integrated into a single transceiver in the UE or theBS.

The antennas 500 a and 500 b transmit signals generated from thetransmitters 100 a and 100 b to the outside or receive signals from theoutside and provide the received signals to the receivers 300 a and 300b. The antennas 500 a and 500 b are also referred to as antenna ports.Each antenna port may correspond to one physical antenna or may beconfigured by a combination of more than one physical antenna element. Asignal transmitted through each antenna port cannot be decomposed anymore by the receiving device 20. A Reference Signal (RS) transmitted incorrespondence to the antenna port defines an antenna port viewed fromthe UE and enables the UE to perform channel estimation for the antennaport, irrespective of whether a channel is a single radio channel fromone physical channel or composite channels from a plurality of physicalantenna elements including the antenna port. That is, an antenna port isdefined such that a channel for transmitting a symbol on the antennaport can be derived from the channel through which another symbol on thesame antenna port is transmitted. If a transmitter and a receiversupport Multiple Input Multiple Output (MIMO) in which data istransmitted and received using a plurality of antennas, each of thetransmitter and the receiver may be connected to two or more antennas.

The processor 400 a or 400 b generally controls overall operation of themodules of the UE or the BS. Especially, the processors 400 a and 400 bmay perform various control functions for implementing the presentinvention, a Medium Access Control (MAC) frame conversion controlfunction based on service characteristics and a propagation environment,a power saving mode function for controlling an idle-mode operation, ahandover function, an authentication and encryption function, etc. Theprocessors 400 a and 400 b may be called controllers, microcontrollers,microprocessors, or microcomputers. Meanwhile, the processors 400 a and400 b may be configured as hardware, firmware, software, or acombination of hardware, firmware, and software. In a hardwareconfiguration, the processors 400 a and 400 b may include ApplicationSpecific Integrated Circuits (ASICs), Digital Signal Processors (DSPs),Digital Signal Processing Devices (DSPDs), Programmable Logic Devices(PLDs), Field Programmable Gate Arrays (FPGAs), etc. which areconfigured to implement the present invention. In a firmware or softwareconfiguration, firmware or software may be configured so as to include amodule, a procedure, a function, etc. that perform the functions oroperations of the present invention. The firmware or software configuredto implement the present invention may be included in the processors 400a and 400 b, or may be stored in the memories 200 a and 200 b andexecuted by the processors 400 a and 400 b.

The transmitters 100 a and 100 b encode and modulate signals and/or datawhich are scheduled by the processors 400 a and 400 b or by schedulersconnected to the processors and which are transmitted to the outside andtransmit the modulated signals and/or data to the antennas 500 a and 500b. For example, the transmitters 100 a and 100 b convert data streams tobe transmitted into K layers through demultiplexing, channel coding, andmodulation. The K layers are transmitted through the antennas 500 a and500 b via transmission processors of the transmitters. The transmitters100 a and 100 b and the receivers 300 a and 300 b of the UE and the BSmay be configured differently according to operations of processing atransmission signal and a received signal.

The memories 200 a and 200 b may store programs for processing andcontrol in the processors 400 a and 400 b and may temporarily storeinput and output information. The memories 200 a and 200 b may functionas buffers. The memories 200 a and 200 b may be configured using a flashmemory type, a hard disk type, a multimedia card micro type, a card typememory (e.g. a Secure Digital (SD) or extreme Digital (XD) memory), aRandom Access Memory (RAM), a Static Random Access Memory (SRAM), aRead-Only Memory (ROM), an Electrically Erasable Programmable Read-OnlyMemory (EEPROM), a Programmable Read-Only Memory (PROM), a magneticmemory, a magnetic disk, an optical disc, etc.

FIG. 2 illustrates an exemplary structure of a transmitter in each ofthe UE and the BS. Operations of the transmitters 100 a and 100 b willbe described below in more detail with reference to FIG. 2.

Referring to FIG. 2, each of the transmitters 100 a and 100 b includescramblers 301, modulation mappers 302, a layer mapper 303, a precoder304, Resource Element (RE) mappers 305, and Orthogonal FrequencyDivision Multiplexing (OFDM) signal generators 306.

The transmitters 100 a and 100 b may transmit more than one codeword.The scramblers 301 scramble the coded bits of each codeword, fortransmission on a physical channel. A codeword may be referred to as adata stream and is equivalent to a data block provided from a MAC layer.The data block provided from the MAC layer is referred to as a transportblock.

The modulation mappers 302 modulate the scrambled bits intocomplex-valued modulation symbols. The modulation mappers 302 maymodulate the scrambled bits to complex-valued modulation symbolsrepresenting positions on signal constellation according to apredetermined modulation scheme. The modulation scheme is not limitedand m-Phase Shift Keying (m-PSK) and m-Quadrature Amplitude Modulation(m-QAM) may be used to modulate the coded data.

The layer mapper 303 maps the complex-valued modulation symbols to oneor several transmission layers.

The precoder 304 may precode the complex modulation symbols on eachlayer, for transmission through the antenna ports. More specifically,the precoder 304 generates antenna-specific symbols by processing thecomplex-valued modulation symbols for multiple transmission antennas500-1 to 500-N_(t) in a MIMO scheme and distributes the antenna-specificsymbols to the RE mappers 305. That is, the precoder 304 maps thetransmission layers to the antenna ports. The precoder 304 may multiplyan output x of the layer mapper 303 by an N_(t)×M_(t) precoding matrix Wand output the resulting product in the form of an N_(t)×M_(F) matrix z.

The RE mappers 305 map/allocate the complex-valued modulation symbolsfor the respective antenna ports to REs. The RE mappers 305 may allocatethe complex-valued modulation symbols for the respective antenna portsto appropriate subcarriers and may multiplex the same according to UEs.

The OFDM signal generators 306 modulate the complex-valued modulationsymbols for the respective antenna ports, that is, the antenna-specificsymbols, through OFDM or Single Carrier Frequency Division Multiplexing(SC-FDM), thereby producing a complex-value time domain OFDM or SC-FDMsymbol signal. The OFDM signal generators 306 may perform Inverse FastFourier Transform (IFFT) on the antenna-specific symbols and insert aCyclic Prefix (CP) into the resulting IFFT time domain symbol. The OFDMsymbol is transmitted through the transmission antennas 500-1 to500-N_(t) to a receiver after digital-to-analog conversion, frequencyup-conversion, etc. The OFDM signal generators 306 may include an IFFTmodule, a CP inserter, a Digital-to-Analog Converter (DAC), a frequencyup-converter, etc.

Meanwhile, if the transmitters 100 a and 100 b adopt SC-FDMA fortransmission of a codeword, the transmitters 100 a and 100 b may includeDiscrete Fourier Transform (DFT) modules 307 (or Fast Fourier Transform(FFT) modules). The DFT modules perform DFT or FFT on theantenna-specific symbols and outputs the DFT/FFT symbols to the REmappers 305. SC-FDMA is a transmission scheme for transmitting signalsby lowering Peak-to-Average Power Ratio (PAPR) or Cubic Metric (CM) ofthe signals. According to SC-FDMA, signals can be transmitted withoutpassing through the non-linear distortion area of a power amplifier.Accordingly, even when the transmitter transmits a signal at lower powerthan power in a conventional OFDM scheme, the receiver can receive asignal satisfying constant intensity and error rate. That is, the powerconsumption of the transmitter can be reduced by SC-FDMA.

In a conventional OFDM signal generator, signals carried on eachsubcarrier are simultaneously transmitted in parallel with each other byMulti-Carrier Modulation (MCM) while passing through IFFT, therebylowering efficiency of a power amplifier. On the other hand, in SC-FDMA,information undergoes DFT/FFT before signals are mapped to subcarriers.Signals passing through the DFT/FFT module 307 have increased PAPR by aDFT/FFT effect. The DFT/FFT-processed signals are mapped to subcarriers,IFFT-processed, and converted into time-domain signals. That is, theSC-FDMA transmitter further performs a DFT or FFT operation prior to theOFDM signal generator so that PAPR of a transmission signal is increasedat the IFFT input stage and is finally reduced while passing againthrough IFFT. This scheme is called DFT-spread OFDM (DFT-s-OFDM) becauseit seems as if the DFT module (or FFT module) 307 is added before theexisting OFDM signal generator.

SC-FDMA should satisfy a single-carrier property. FIG. 3 illustratesexamples of mapping input symbols to subcarriers in the frequency domainwhile satisfying the single-carrier property. If DFT symbols areallocated to subcarriers according to one of the schemes illustrated inFIGS. 3( a) and 3(b), a transmission signal satisfying thesingle-carrier property may be obtained. FIG. 3( a) illustrateslocalized mapping and FIG. 3( b) illustrates distributed mapping.

Meanwhile, the transmitters 100 a and 100 b may adopt clusteredDFT-spread-OFDM (DFT-s-OFDM). Clustered DFT-s-OFDM is a modified versionof conventional SC-FDMA. In clustered DFT-s-OFDM, a signal passingthrough the DFT/FFT module 307 and the precoder 304 is divided into apredetermined number of sub-blocks and mapped to subcarriers in anon-contiguous manner. FIGS. 4 to 6 illustrate examples of mapping aninput symbol to a single carrier by clustered DFT-s-OFDM.

FIG. 4 illustrates a signal processing operation for mapping DFTprocessed output samples to a single carrier in clustered SC-FDMA. FIGS.5 and 6 illustrate signal processing operations for mapping DFTprocessed output samples to multiple carriers in clustered SC-FDMA. FIG.4 illustrates the application of intra-carrier clustered SC-FDMA,whereas FIGS. 5 and 6 illustrate the application of inter-carrierclustered SC-FDMA. FIG. 5 illustrates signal generation through a singleIFFT block in the case where subcarrier spacings between contiguouscomponent subcarriers are aligned in a situation in which componentcarriers are contiguously allocated in the frequency domain. FIG. 6illustrates signal generation through a plurality of IFFT blocks in asituation in which component carriers are non-contiguously allocated inthe frequency domain.

FIG. 7 illustrates a signal processing operation in segmented SC-FDMA.

As the number of DFT blocks is equal to the number of IFFT blocks andthus the DFT blocks and the IFFT blocks are in one-to-onecorrespondence, segmented SC-FDMA is a simple extension of the DFTspreading and IFFT subcarrier mapping structure of conventional SC-FDMAand may be expressed as NxSC-FDMA or N×DFT-s-OFDMA. In this disclosure,segmented SC-FDMA includes all these terms. Referring to FIG. 7, insegmented SC-FDMA, all modulation symbols in the time domain are dividedinto N groups (where N is an integer greater than 1) and subjected to aDFT process in units of a group in order to relieve single-carrierproperty constraints.

Referring back to FIG. 2, the receivers 300 a and 300 b operate in thereverse order to the operation of the transmitters 100 a and 100 b. Thereceivers 300 a and 300 b decode and demodulate radio signals receivedthrough the antennas 500 a and 500 b from the outside and transfer thedemodulated signals to the processors 400 a and 400 b. The antenna 500 aor 500 b connected to each of the receivers 300 a and 300 b may includeN_(r) reception antennas. A signal received through each receptionantenna is restored into a baseband signal and then recovered to theoriginal data stream transmitted by the transmitter 100 a or 100 bthrough multiplexing and MIMO demodulation. Each of the receivers 300 aand 300 b may include a signal recoverer for recovering a receivedsignal into a baseband signal, a multiplexer for multiplexing a receivedand processed signal, and a channel demodulator for demodulating themultiplexed signal stream to a codeword. The signal recoverer, themultiplexer, and the channel demodulator may be configured as anintegrated module for performing their functions or independent modules.More specifically, the signal recoverer may include an Analog-to-DigitalConverter (ADC) for converting an analog signal to a digital signal, aCP remover for removing a CP from the digital signal, an FFT module forgenerating a frequency-domain symbol by performing FFT on the CP-removedsignal, and an RE demapper/equalizer for recovering antenna-specificsymbols from the frequency-domain symbol. The multiplexer recoverstransmission layers from the antenna-specific symbols and the channeldemodulator recovers the codeword transmitted by the transmitter fromthe transmission layers.

Meanwhile, if the receivers 300 a and 300 b receive signals transmittedby SC-FDMA described with reference to FIGS. 3 to 7, each of thereceivers 300 a and 300 b further includes an IFFT module. The IDFT/IFFTmodule IDFT/IFFT-processes the antenna-specific symbols recovered by theRE demapper and outputs the IDFT/IFFT symbol to the multiplexer.

While it has been described in FIGS. 1 to 7 that each of thetransmitters 100 a and 100 b includes the scramblers 301, the modulationmappers 302, the layer mapper 303, the precoder 304, the RE mappers 305,and the OFDM signal generators 306, it may be further contemplated thatthe scramblers 301, the modulation mappers 302, the layer mapper 303,the precoder 304, the RE mappers 305, and the OFDM signal generators 306are incorporated into each of the processors 400 a and 400 b of thetransmitters 100 a and 100 b. Likewise, while it has been described inFIGS. 1 to 7 that each of the receivers 300 a and 300 b includes thesignal recoverer, the multiplexer, and the channel demodulator, it maybe further contemplated that the signal recoverer, the multiplexer, andthe channel demodulator are incorporated into each of the processors 400a and 400 b of the receivers 300 a and 300 b. For convenience ofdescription, the following description will be given on the premise thatthe scramblers 301, the modulation mappers 302, the layer mapper 303,the precoder 304, the RE mappers 305, and the OFDM signal generators 306(in case of the SC-FDMA scheme, the DFT modules 307 are furtherincluded) are included in the transmitters 100 a and 100 b configuredseparately from the processors 400 a and 400 b that control operationsthereof, and the signal recoverer, the multiplexer, and the channeldemodulator are included in the receivers 300 a and 300 b configuredseparately from the processors 400 a and 400 b that control operationsthereof. However, embodiments of the present invention are applicable inthe same manner even though the scramblers 301, the modulation mappers302, the layer mapper 303, the precoder 304, the RE mappers 305, and theOFDM generators 306 (and 307) are included in the processors 400 a and400 b and the signal recoverer, the multiplexer, and the channeldemodulator (in case of the SC-FDMA scheme, the IFFT module is furtherincluded) are included in the processors 400 a and 400 b.

FIG. 8 illustrates exemplary radio frame structures used in a wirelesscommunication system. Specifically, FIG. 8( a) illustrates a radio frameof Frame Structure type 1 (FS-1) in a 3GPP LTE/LTE-A system and FIG. 8(b) illustrates a radio frame of Frame Structure type 2 (FS-2) in the3GPP LTE/LTE-A system. The frame structure of FIG. 8( a) may be appliedto Frequency Division Duplex (FDD) mode and half-FDD (H-FDD) mode, whilethe frame structure of FIG. 8( b) may be applied to Time Division Duplex(TDD) mode.

Referring to FIG. 8, a radio frame has a length of 10 ms (307200 Ts) in3GPP LTE/LTE-A, including 10 equally sized subframes. The 10 subframesof the radio frame may be numbered. Herein, T_(s) is a sampling time,expressed as T_(s)=1/(2048×15 kHz). Each subframe is 1 ms long,including two slots. The 20 slots of the radio frame may be sequentiallynumbered from 0 to 19. Each slot has a length of 0.5 ms. A time requiredto transmit one subframe is defined as a Transmission Time Interval(TTI). Time resources may be identified by a radio frame number (or aradio frame index), a subframe number (or a subframe index), and a slotnumber (or a slot index).

Different radio frames may be configured according to duplex mode. Forexample, in FDD mode, since downlink transmission and uplinktransmission are distinguished by frequency, the radio frame includeseither downlink subframes or uplink subframes.

On the other hand, in TDD mode, since downlink transmission and uplinktransmission are distinguished by time, the subframes in the frame aredivided into downlink subframes and uplink subframes. Table 1 shows anexemplary uplink-downlink configuration in TDD mode.

TABLE 1 Uplink-downlink Subframe number configuration 0 1 2 3 4 5 6 7 89 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 DS U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U UU D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframe,and S denotes a special subframe. The special subframe includes threefields of a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP), anUplink Pilot Time Slot (UpPTS). DwPTS is a time slot reserved fordownlink transmission and UpPTS is a time slot reserved for uplinktransmission.

FIG. 9 illustrates an exemplary downlink/uplink (DL/UL) slot structurein a wireless communication system. In particular, FIG. 9 illustratesthe structure of a resource grid of a 3GPP LTE/LTE-A system. Oneresource grid exists per antenna port.

Referring to FIG. 9, a slot includes a plurality of Orthogonal FrequencyDivision Multiplexing (OFDM) symbols in a time domain and includes aplurality of Resource Blocks (RBs) in a frequency domain. The OFDMsymbol may mean one symbol duration. An RB includes a plurality ofsubcarriers in the frequency domain. An OFDM symbol may be called anOFDM symbol, an SC-FDM symbol, etc. according to a multiple accessscheme. The number of OFDM symbols per slot may vary depending on achannel bandwidth and cyclic Prefix (CP) length. For instance, one slotincludes 7 OFDM symbols in case of a normal CP, whereas one slotincludes 6 OFDM symbols in case of an extended CP. While a subframe isshown in FIG. 8 as having a slot with 7 OFDM symbols for illustrativepurposes, embodiments of the present invention are also applicable tosubframes with any other number of OFDM symbols. A resource includingone OFDM symbol by one subcarrier is referred to as a Reference Element(RE) or a tone.

Referring to FIG. 9, a signal transmitted in each slot may be describedby a resource grid including N^(DL/UL) _(RB)N^(RB) _(sc) subcarriers andN^(DL/UL) _(symb) OFDM or SC-FDM symbols. N^(DL) _(RB) represents thenumber of RBs in a DL slot and N^(UL) _(RB) represents the number of RBsin a UL slot. N^(DL) _(RB) and N^(UL) _(RB) depend on a DL transmissionbandwidth and a UL transmission bandwidth, respectively. Each OFDMsymbol includes N^(DL/UL) _(RB)N^(RB) _(sc) subcarriers in the frequencydomain. The number of subcarriers in one carrier is determined accordingto FFT magnitude. The type of the subcarrier may be divided into a datasubcarrier for data transmission, an RS subcarrier for RS transmission,and a null subcarrier for a guard band and a DC component. The nullsubcarrier for the DC component remains unused and is mapped to acarrier frequency f₀ in a process of generating an OFDM signal. Thecarrier frequency is also called a center frequency. N^(DL) _(symb)denotes the number of OFDM or SC-FDMA symbols in a DL slot, N^(DL)_(symb) denotes the number of OFDM or SC-FDMA symbols in a UL slot, andN^(RB) _(sc) denotes the number of subcarriers configuring one RB.

In other words, a Physical Resource Block (PRB) is defined as N^(DL/UL)_(symb) consecutive OFDM symbols or SC-FDMA symbols in the time domainby N^(RB) _(sc) consecutive subcarriers in the frequency domain.Therefore, one PRB includes N^(DL/UL) _(symb)×N^(RB) _(sc) REs.

Each RE in the resource grid may be uniquely identified by an index pair(k, l) in a slot. k is a frequency-domain index ranging from 0 toN^(DL/UL) _(RB)×N^(RB) _(sc)−1 and l is a time-domain index ranging from0 to N^(DL/UL) _(symb)−1.

FIG. 10 illustrates an exemplary DL subframe structure in a wirelesscommunication system.

Referring to FIG. 10, each subframe may be divided into a control regionand a data region. The control region includes one or more OFDM symbolsstarting from the first OFDM symbol. The number of OFDM symbols used inthe control region in the subframe may be independently configured ineach subframe. Information about the number of OFDM symbols istransmitted through a Physical Control Format Indicator Channel(PCFICH). A BS may transmit various control information to a UE(s)through the control region. For control information transmission, aPhysical Downlink Control Channel (PDCCH), a PCFICH, and a PhysicalHybrid automatic repeat request Indicator Channel (PHICH) may beallocated to the control region.

The BS transmits information associated with resource allocation of aPaging Channel (PCH) and a Downlink-Shared Channel (DL-SCH) which aretransport channels, a UL scheduling grant, Hybrid Automatic RepeatRequest (HARQ) information, a Downlink Assignment Index (DAI), etc. toeach UE or UE group on the PDCCH.

The BS may transmit data for UEs or UE groups through the data region.Data transmitted through the data region is also referred to as userdata. For transmission of user data, a Physical Downlink Shared Channel(PDSCH) may be allocated to the data region. The PCH and DL-SCH aretransmitted through the PDSCH. The UE may read data transmitted throughthe PDSCH by decoding control information transmitted through the PDCCH.Information indicating to which UE or UE group PDSCH data is transmittedand information indicating how the UE or UE group should receive anddecode the PDSCH data are transmitted over the PDCCH. For example, it isassumed that a specific PDCCH is CRC-masked with a Radio NetworkTemporary Identity (RNTI) ‘A’ and information about data transmittedusing a radio resource ‘B’ (e.g. frequency location) and using transportformat information ‘C’ (e.g. transmission block size, modulation scheme,coding information, etc.) is transmitted through a specific subframe.Then, a UE in a cell monitors the PDCCH using RNTI information thereof.The UE having the RNTI ‘A’ receives the PDCCH and receives the PDSCHindicated by ‘B’ and ‘C’ through information of the received PDCCH.

A plurality of PDCCHs may be transmitted in the control region. A UE maymonitor the plurality of PDCCHs to detect a PDCCH thereof. DownlinkControl Information (DCI) carried by the PDCCH may be different in sizeand purpose according to a DCI format and in size according to codingrate.

The DCI format may be independently applied for each UE, and the PDCCHsof multiple UEs may be multiplexed in one subframe. The PDCCH of each UEmay be independently channel-coded so that a Cyclic Redundancy Check(CRC) can be added to the PDCCH. The CRC is masked with a uniqueidentifier of each UE so that each UE can receive the PDCCH thereof.However, since the UE is essentially unaware of the position to whichthe PDCCH thereof is transmitted, the UE is required to perform blinddetection (also referred to as blind decoding) on all PDCCHs of thecorresponding DCI format in every subframe, until the PDCCH having theidentifier thereof is received.

FIG. 11 illustrates an exemplary UL subframe structure in a wirelesscommunication system

Referring to FIG. 11, a UL subframe may be divided into a control regionand a data region in the frequency domain. One or multiple PhysicalUplink Control Channels (PUCCHs) may be allocated to the control regionto carry Uplink Control Information (UCI). One or multiple PhysicalUplink Shared Channels (PUSCHs) may be allocated to the data region tocarry user data. If the UE adopts an SC-FDMA scheme for uplinktransmission, the PUCCH and the PUSCH cannot be simultaneouslytransmitted in order to maintain a single-carrier property.

The UCI carried by the PUCCH may be different in size and purposeaccording to a PUCCH format and in size according to coding rate. Forexample, the PUCCH format may be defined as follows.

TABLE 2 Number of PUCCH Modulation bits per format scheme subframe UsageEtc. 1 N/A N/A (exist SR (Scheduling or absent) Request) 1a BPSK 1ACK/NACK or One codeword SR + ACK/NACK 1b QPSK 2 ACK/NACK or Twocodeword SR + ACK/NACK 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK(extended CP) 2a QPSK + 21 CQI/PMI/RI + Normal CP BPSK ACK/NACK only 2bQPSK + 22 CQI/PMI/RI + Normal CP QPSK ACK/NACK only 3 QPSK 48 ACK/NACKor SR + ACK/NACK or CQI/PMI/RI + ACK/NACK

In a UL subframe, subcarriers distant from a Direct Current (DC)subcarrier are used as the control region. In other words, subcarrierslocated at both ends of a UL transmission bandwidth are assigned for ULcontrol information transmission. DC subcarriers are reserved withoutbeing used in signal transmission and are mapped to a carrier frequencyf₀ in a frequency up-conversion process caused by the OFDM/SC-FDMAsignal generator 306.

A PUCCH for a UE is allocated to an RB pair in a subframe. The RBs ofthe RB pair occupy different subcarriers in two slots. This is calledfrequency hopping of an RB pair allocated to a PUCCH over a slotboundary. However, if frequency hopping is not used, an RB pair occupiesthe same subcarriers. Irrespective of the frequency hopping, a PUCCH forone UE is assigned to an RB pair in one subframe and therefore the samePUCCH is transmitted once through one RB in each slot, a total of twotimes, in one UL subframe.

Hereinafter, an RB pair used for each PUCCH transmission of one subframeis called a PUCCH region or a PUCCH resource. In addition, forconvenience of description, a PUCCH carrying Acknowledgement/NegativeAcknowledgement (ACK/NACK) is referred to as an ACK/NACK PUCCH, a PUCCHcarrying Channel Quality Indicator (CQI)/Precoding Matrix Indicator(PMI)/Rank Information (RI) is referred to as a Channel StateInformation (CSI) PUCCH, and a PUCCH carrying Scheduling Request (SR) isreferred to as an SR PUCCH.

The UE is assigned PUCCH resources for UCI transmission from the BSaccording to the explicit or implicit scheme.

UCI such as ACK/NACK, CQI, PMI, RI, SR, etc. may be transmitted over acontrol region of the UL subframe.

In a wireless communication system, the BS and the UE mutuallytransmit/receive signals or data. If the BS/UE transmits data to theUE/BS, the UE/BS decodes the received data. If the data is successfullydecoded, ACK is transmitted to the BS/UE. If data decoding fails, NACKis transmitted to the BS/UE. In the 3GPP LTE system, the UE receives adata unit (e.g., PDSCH) from the BS and transmits ACK/NACK to the dataunit to the BS through implicit PUCCH resources decided by PDCCHresources carrying scheduling information for the data unit.

FIG. 12 illustrates an example for determining PUCCH resources forACK/NACK.

In the LTE system, a PUCCH resource for ACK/NACK is not previouslyallocated to each UE and multiple UEs located in a cell use a pluralityof PUCCH resources in a divided manner at every time point.Specifically, the PUCCH resource used for ACK/NACK transmission of theUE is implicitly determined based on a PDCCH that carries schedulinginformation of a PDSCH that carries corresponding DL data. An entireregion in which a PDCCH is transmitted in a DL subframe includes aplurality of Control Channel Elements (CCEs) and a PDCCH transmitted tothe UE includes one or more CCEs. Each CCE includes a plurality ofResource Element Groups (REGs) (e.g. 9 REGs). One REG is comprised offour contiguous REs when a Reference Signal (RS) is excluded. The UEtransmits ACK/NACK through an implicit PUCCH resource that is derived orcalculated using a function of a specific CCE index (e.g. the first orlowest CCE index) from among indexes of CCEs that constitute the PDCCHreceived by the UE.

Referring to FIG. 12, each PUCCH resource index corresponds to a PUCCHresource for ACK/NACK. As shown in FIG. 12, assuming that PDSCHscheduling information is transmitted to the UE through a PDCCHconsisting of CCEs numbered 4 to 6, the UE transmits ACK/NACK to the BSthrough a PUCCH derived or calculated from CCE number 4, which is thelowest CCE of the PDCCH, for example, through PUCCH number 4. FIG. 12shows an example in which up to M′ CCEs are present in a DL subframe andup to M PUCCH resources are present in a UL subframe. Although M′ may beequal to M, M′ may be different from M and CCEs and PUCCH resources maybe mapped in an overlapping manner.

For example, a PUCCH resource index may be determined as follows.n _(PUCCH) ⁽¹⁾ =n _(CCE) +N _(PUCCH) ⁽¹⁾  [Equation 1]

Here, n⁽¹⁾ _(PUCCH) is a PUCCH resource index for ACK/NACK transmission,N⁽¹⁾ _(PUCCH) is a signaling value received from a higher layer, andn_(CCE) denotes the lowest CCE index used for PDCCH transmission.

FIG. 13 illustrates exemplary communication in a single carriersituation. FIG. 13 may correspond to an example of communication in theLTE system.

Referring to FIG. 13, a general FDD wireless communication systemtransmits and receives data through one DL band and one UL bandcorresponding to the DL band. A BS and a UE transmit and receive dataand/or control information scheduled in a subframe unit. The data istransmitted and received through a data region configured in UL/DLsubframes and the control information is transmitted and receivedthrough a control region configured in the UL/DL subframes. To this end,the UL/DL subframes carry signals on various physical channels. Althougha description of FIG. 13 is given based on an FDD scheme forconvenience, the above description may also be applied to a TDD schemeby dividing the radio frame of FIG. 8 into UL and DL frames in the timedomain.

FIG. 14 illustrates exemplary communication in a multi-carriersituation.

The LTE-A system uses carrier aggregation or bandwidth aggregation thatuses a wider UL/DL bandwidth by aggregating a plurality of UL/DLfrequency blocks in order to employ a wider frequency band. Amulticarrier system or Carrier Aggregation (CA) system refers to asystem aggregating a plurality of carriers each having a narrowerbandwidth than a target bandwidth, for broadband support. When aplurality of carriers having a narrower bandwidth than a targetbandwidth is aggregated, the bandwidth of the aggregated carriers may belimited to a bandwidth used in a legacy system in order to maintainbackward compatibility with the legacy system. For example, an LTEsystem may support bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz and theLTE-Advanced (LTE-A) system improved from the LTE system may supportbandwidths wider than 20 MHz using the bandwidths supported in the LTEsystem. In addition, a new bandwidth may be defined to support CAirrespective of bandwidth used in the legacy system. The termmulticarrier is used interchangeably with the terms CA and bandwidthaggregation. Contiguous CA and non-contiguous CA are collectivelyreferred to as CA. For reference, when only one Component Carrier (CC)is used for communication in TDD, this corresponds to communication inthe single carrier situation (non-CA) of FIG. 13. A UL CC and a DL CCare also referred to as UL resources and DL resources, respectively.

For example, referring to FIG. 14, five CCs, each of 20 MHz, may beaggregated on each of UL and DL to support a bandwidth of 100 MHz. Therespective CCs may be contiguous or non-contiguous in the frequencydomain. For convenience, FIG. 14 shows the case in which the bandwidthof a UL CC is the same as the bandwidth of a DL CC and the two aresymmetrical. However, the bandwidth of each CC may be independentlydetermined. For example, the bandwidth of the UL CC may be configured ina manner of 5 MHz (UL CC0)+20 MHz (UL CC1)+20 MHz (UL CC2)+20 MHz (ULCC3)+5 MHz (UL CC4). It is also possible to configure asymmetric CA inwhich the number of UL CCs is different from the number of DL CCs.Asymmetric CA may be generated due to limitation of available frequencybands or may be intentionally formed by network configuration. Forexample, even when the BS manages X DL CCs, a frequency band which canbe received by a specific UE may be limited to Y (≦X) DL CCs. In thiscase, the UE needs to monitor DL signals/data transmitted through the YCCs. In addition, even when the BS manages L UL CCs, a frequency bandwhich can be received by a specific UE may be limited to M (≦L) UL CCs.The limited DL CCs or UL CCs for a specific UE are referred to asserving UL or DL CCs configured in a specific UE. The BS may allocate aprescribed number of CCs to the UE by activating some or all of the CCsmanaged by the BS or by deactivating some CCs managed by the BS. The BSmay change the activated/deactivated CCs and change the number ofactivated/deactivated CCs. Meanwhile, the BS may cell-specifically orUE-specifically configure Z DL CCs (where 1≦Z≦y≦X) that the UE shouldfirst monitor/receive as main DL CCs. Further, the BS maycell-specifically or UE-specifically configure N UL CCs (where 1≦N≦M≦L)that the UE should first transmit as main UL CCs. In this way, therestricted main DL or UL CCs for a specific UE are also referred to asserving UL or DL CCs configured in a specific UE. Various parameters forCA may be configured cell-specifically, UE group-specifically, orUE-specifically.

Once the BS allocates available CCs to the UE cell-specifically orUE-specifically, at least one of the allocated CCs is not deactivated,unless overall CC allocation to the UE is reconfigured or the UE ishanded over. Hereinafter, the CC which is not deactivated unless theoverall CC allocation to the UE is reconfigured is referred to as aPrimary CC (PCC) and a CC that the BS can freely activate/deactivate isreferred to as a Secondary CC (SCC). Single carrier communication usesone PCC for communication between the UE and the BS and does not use theSCC for communication. Meanwhile, the PCC and SCC may also bedistinguished based on control information. For example, specificcontrol information may be set to be transmitted/received only through aspecific CC. Such a specific CC may be referred to as a PCC and theother CC(s) may be referred to as SCC(s). For instance, controlinformation transmitted through a PUCCH may correspond to such specificcontrol information. Thus, if control information transmitted on thePUCCH can be transmitted to the BS from the UE only through the PCC, aUL CC in which the PUCCH of the UE is present may be referred to as a ULPCC and the other UL CC(s) may be referred to as UL SCC(s). As anotherexample, if a UE-specific CC is used, the specific UE may receive a DLSynchronization Signal (SS) from the BS as specific control information.In this case, a DL CC with which the specific UE establishessynchronization of initial DL time by receiving the DL SS (i.e. a DL CCused for attempting to access a network of the BS) may be referred to asa DL PCC and the other DL CC(s) may be referred to as DL SCC(s). In acommunication system according to LTE-A release-10, multicarriercommunication uses one PCC and no SCC or one or more SCC(s) per UE.However, this is the definition according to LTE-A and communicationusing multiple PCCs per UE will be able to be permitted in the future.The PCC may be referred to as a primary CC, an anchor CC, or a primarycarrier and the SCC may be referred to as a secondary CC or a secondarycarrier.

LTE-A uses the concept of cells to manage radio resources. A cell isdefined as a combination of DL resources and UL resources, that is, a DLCC and a UL CC. Here, the UL resources are not an indispensiblecomponent. However, this is defined in the current LTE-A standard and,in the future, it may be permitted that a cell is configured using theUL resources alone. Accordingly, the cell can be configured with the DLresources alone, or with both the DL resources and UL resources. When CAis supported, linkage between carrier frequency of the DL resources (orDL CC) and carrier frequency of the UL resources (or UL CC) may beindicated by system information. For example, a combination of the DLresources and the UL resources may be indicated by a System InformationBlock type 2 (SIB2). Here, the carrier frequency refers to a centerfrequency of each cell or CC. A cell that operates on a primaryfrequency (or PCC) may be referred to as a Primary Cell (PCell) and acell(s) that operates on a secondary frequency (or SCC) may be referredto as a Secondary Cell(s) (SCell(s)). The primary frequency (or PCC)refers to a frequency (or CC) used for the UE to perform an initialconnection establishment or connection re-establishment procedure. PCellmay refer to a cell indicated during a handover process. The secondaryfrequency (or SCC) refers to a frequency (or CC) that is configurableafter RRC connection setup is performed and is usable to provideadditional radio resources. The PCell and SCell may be collectivelyreferred to as a serving cell. Accordingly, for a UE that is in anRRC_CONNECTED state, for which CA is not configured or CA is notsupported, only one serving cell comprised of only the PCell is present.Meanwhile, for a UE in an RRC_CONNECTED state, for which CA isconfigured, one or more serving cells may be present and all servingcells may include one PCell and one or more SCells. However, in thefuture, it may be permitted that the serving cell includes a pluralityof PCells. For CA, a network may configure one or more SCells for a UEthat supports CA in addition to the PCell initially configured in theconnection establishment procedure after an initial security activationprocedure is initiated. However, even if the UE supports CA, the networkmay configure only the PCell for the UE, without adding the SCells. ThePCell may be referred to as a primary CC, an anchor CC, or a primarycarrier and the SCell may be referred to as a secondary CC or asecondary carrier.

In a multicarrier system, the BS may transmit a plurality of data unitsto the UE in a given cell(s) (or CC(s)) and the UE may transmit ACK/NACKsignals for the plurality of data units in one subframe. The UE may beallocated one or plural cells (or DL CCs) for receiving a PDSCH for DLdata reception. A cell (or DL CC(s)) for the UE may be semi-staticallyconfigured or reconfigured by RRC signaling. Moreover, a cell (or DLCC(s)) for the UE may be dynamically activated/deactivated by L1/L2(Medium Access Control (MAC)) control signaling. Therefore, the maximumnumber of ACK/NACK bits to be transmitted by the UE varies according tocells (or DL CCs) available to the UE. That is, the maximum number ofACK/NACK bits to be transmitted by the UE is configured/reconfigured byRRC or varies with an activated DL CC (or configured serving cell(s)) byL1/L2 signaling.

FIG. 15 explains a concept that one MAC layer manages multiple carriersin a BS. FIG. 16 explains a concept that one MAC layer manages multiplecarriers in a UE.

Referring to FIG. 15 and FIG. 16, one MAC layer manages one or morefrequency carriers so as to perform transmission and reception. Sincethe frequency carriers managed by one MAC layer need not be contiguous,more flexible resource management is possible. In FIGS. 15 and 16, onephysical layer (PHY) means one CC for convenience. Here, one PHY doesnot necessarily mean an independent Radio Frequency (RF) device. Ingeneral, one independent RF device means one PHY but is not limitedthereto. One RF device may include several PHYs.

FIG. 17 explains a concept that a plurality of MAC layers managesmultiple carriers in a BS and FIG. 18 explains a concept that aplurality of MAC layers manages multiple carriers in a UE. FIG. 19explains another concept that a plurality of MAC layers manages multiplecarriers in a BS and FIG. 20 explains another concept that a pluralityof MAC layers manages multiple carriers in a UE.

In addition to the structures as shown in FIGS. 15 and 16, multiple MAClayers rather than one MAC layer may control a plurality of CCs as shownin FIGS. 17 to 20.

As shown in FIGS. 17 and 18, each MAC layer may control each carrier inone-to-one correspondence. As shown in FIGS. 19 and 20, each MAC layermay control each carrier in one-to-one correspondence with respect topartial carriers and one MAC layer may control one or more carriers withrespect to the other carriers.

The system applied to the above description is a system supporting onecarrier to N multiple carriers and carriers may be contiguous ornon-contiguous carriers, regardless of UL/DL. A TDD system is configuredto manage N carriers each including DL and UL transmission and an FDDsystem is configured to respectively use multiple carriers in UL and DL.The FDD system may support asymmetric CA in which the numbers ofaggregated carriers and/or the bandwidths of carriers in UL and DL aredifferent.

If the number of CCs aggregated in UL is equal to the number of CCsaggregated in DL, it is possible to configure CCs such that all CCs arecompatible with CCs used in a legacy system. However, CCs that do notsupport compatibility are not excluded from the present invention.

For convenience of description, although description will be given underthe assumption that when a PDCCH is transmitted on a DL CC #0, a PDSCHcorresponding to the PDCCH is transmitted on the DL CC #0, it isapparent that cross-carrier scheduling may be applied so that the PDSCHis transmitted on a DL CC different from the DL CC #0.

FIGS. 21 and 22 illustrate slot level structures of PUCCH formats 1a and1b for ACK/NACK transmission.

FIG. 21 illustrates PUCCH formats 1a and 1b in case of normal CP andFIG. 22 illustrates PUCCH formats 1a and 1b in case of extended CP. Thesame control information is repeated on a slot basis in a subframe inPUCCH formats 1a and 1b. A UE transmits ACK/NACK signals throughdifferent resources of different Cyclic Shifts (CSs) (frequency-domaincodes) and Orthogonal Cover (OC) or Orthogonal Cover Codec (OCCc)(time-domain spreading codec) of a Computer-Generated Constant AmplitudeZero Auto Correlation (CG-CAZAC) sequence. An OC includes, for example,a Walsh/DFT orthogonal code. If the number of CSs is 6 and the number ofOCs is 3, a total of 18 UEs may be multiplexed in the same PhysicalResource Block (PRB) based on a single antenna. Orthogonal sequences w0,w1, w2, and w3 are applied in an arbitrary time domain (after FFTmodulation) or in an arbitrary frequency domain (before FFT modulation).PUCCH format 1 for SR transmission and PUCCH formats 1a and 1b are thesame in slot level structure and different in modulation scheme.

PUCCH resources comprised of a CS, an OC, and a PRB may be allocated toa UE by Radio Resource Control (RRC) signaling, for SR transmission andfor ACK/NACK feedback for Semi-Persistent Scheduling (SPS). As explainedwith reference to FIG. 12, for dynamic ACK/NACK (or ACK/NACK fornon-persistent scheduling) feedback or ACK/NACK feedback for the PDCCHindicating SPS release, a PUCCH resource may be implicitly allocated toa UE using the lowest CCE index of a PDCCH corresponding to a PDSCH or aPDCCH for SPS release.

FIG. 23 illustrates a scenario of transmitting UCI in a wirelesscommunication system supporting CA. For convenience of description, itis assumed in this example that UCI is ACK/NACK (A/N). However, UCI mayinclude control information such as CSI (e.g. CQI, PMI, and RI) andscheduling request information (e.g. SR), without restriction.

FIG. 23 illustrates exemplary asymmetrical CA in which five DL CCs arelinked to a single UL CC. This asymmetrical CA may be set from theperspective of transmitting UCI. That is, DL CC-UL CC linkage for UCImay be set to be different from DL CC-UL CC linkage for data. Forconvenience, if it is assumed that each DL CC can carry up to twocodewords and the number of ACKs/NACKs for each CC depends on themaximum number of codewords set per CC (e.g. if a BS sets up to twocodewords for a specific CC, even though a specific PDCCH uses only onecodeword on the CC, ACKs/NACKs for the CC are set to 2 which is themaximum number of codewords on the CC), at least two UL ACK/NACK bitsare needed for each DL CC. In this case, at least 10 ACK/NACK bits areneeded to transmit ACKs/NACKs to data received on five DL CCs on asingle UL CC. If a Discontinuous Transmission (DTX) state is also to beindicated for each DL CC, at least 12 bits (=5⁶=3125=11.61 bits) arerequired for ACK/NACK transmission. Since up to two ACK/NACK bits areavailable in the conventional PUCCH formats 1a and 1b, this structurecannot transmit increased ACK/NACK information. While CA is given as anexample of a cause to increase the amount of UCI, this situation mayalso occur due to an increase in the number of antennas and existence ofa backhaul subframe in a TDD system and a relay system. Similarly toACK/NACK transmission, the amount of control information to betransmitted is also increased when control information related to aplurality of DL CCs is transmitted on a single UL CC. For example,transmission of CQI/PMI/RI information related to a plurality of DL CCsmay increase UCI payload.

In FIG. 23, a UL anchor CC (also referred to as a UL PCC or a UL primaryCC) is a CC on which a PUCCH or UCI is transmitted and may becell-specifically/UE-specifically determined. In addition, a DTX statemay be explicitly fed back or may be fed back so as to share the samestate as NACK.

Hereinafter, a method for efficiently transmitting increased UCI will beproposed with reference to the drawings. Specifically, a new PUCCHformat/signal processing operation/resource allocation method fortransmitting increased UCI are proposed. The new PUCCH format proposedby the present invention is referred to as a CA PUCCH format, or PUCCHformat 3 relative to PUCCH format 2 defined in legacy LTE Release 8/9.The technical features of the proposed PUCCH format may be easilyapplied to any physical channel (e.g. a PUSCH) that can deliver UCI inthe same manner or in a similar manner. For example, an embodiment ofthe present invention is applicable to a periodic PUSCH structure forperiodically transmitting control information or an aperiodic PUSCHstructure for aperiodically transmitting control information.

The following drawings and embodiment of the present invention will bedescribed, focusing on the case of using the UCI/RS symbol structure ofPUCCH formats 1/1a/1b (a normal CP) of legacy LTE as a subframe/slotlevel UCI/RS symbol structure applied to PUCCH format 3. However, thesubframe/slot level UCI/RS symbol structure of PUCCH format 3 isexemplarily defined for convenience and the present invention is notlimited to such a specific structure. The number and positions of UCI/RSsymbols may be changed freely in PUCCH format 3 of the present inventionaccording to system design. For example, PUCCH format 3 according to anembodiment of the present invention may be defined using the RS symbolstructure of PUCCH formats 2/2a/2b of legacy LTE.

PUCCH format 3 according to the embodiment of the present invention maybe used to transmit UCI of any type or size. For example, informationsuch as HARQ ACK/NACK, a CQI, a PMI, an RI, and an SR may be transmittedin PUCCH format 3 according to the embodiment of the present inventionmay. This information may have a payload of any size. For convenience ofdescription, the following description will focus on transmission ofACK/NACK information in PUCCH format 3 according to the presentinvention.

FIGS. 24 to 27 illustrate a PUCCH format structure for feeding back aplurality of ACK/NACK bits and a signal processing operation therefor.For example, the PUCCH format may be used when a plurality ACK/NACK bitsis fed back in a multi-carrier environment. Such a PUCCH format may bereferred to as PUCCH format 3 to distinguish it from a conventionalseries of PUCCH formats 1 and 2.

FIGS. 24 to 27 illustrate a DFT-based PUCCH format structure. Accordingto the DFT-based PUCCH structure, a PUCCH is DFT-precoded and atime-domain OC is applied thereto at an SC-FDMA level prior totransmission. Hereinafter, the DFT-based PUCCH format will be referredto as PUCCH format 3.

FIG. 24 illustrates an exemplary structure of PUCCH format 3 using an OCof Spreading Factor (SF) of 4 (SF=4). Referring to FIG. 24, a channelcoding block channel-encodes information bits a_(—)0, a_(—)1, . . . ,a_M−1 (e.g. multiple ACK/NACK bits) and generates coded bits (or acodeword), b_(—)0, b_(—)1, . . . , b_N−1. M is the size of informationbits and N is the size of coded bits. The information bits include UCI,for example, multiple ACKs/NACKs to a plurality of data (or PDSCHs)received on a plurality of DL CCs. Herein, the information bits a_(—)0,a_(—)1, . . . , a_M−1 are jointly encoded irrespective of thetype/number/size of UCI constituting the information bits. For example,if the information bits include multiple ACKs/NACKs for a plurality ofDL CCs, channel coding is performed on the entire bit information,rather than per DL CC or per individual ACK/NACK bit. A single codewordis generated by channel coding. Channel coding includes, but is notlimited to, repetition, simplex coding, Reed Muller (RM) coding,punctured RM coding, Tail-Biting Convolutional Coding (TBCC),Low-Density Parity-Check (LDPC) coding, or turbo coding. Although notshown, the coded bits may be rate-matched, in consideration ofmodulation order and the amount of resources. The rate matching functionmay be partially incorporated into the channel coding block orimplemented in a separate functional block. For example, the channelcoding block may obtain a single codeword by performing (32, 0) RMcoding with respect to a plurality of control information and mayperform cyclic buffer rate-matching.

A modulator generates modulation symbols c_(—)0, c_(—)1, . . . , c_L−1by modulating the coded bits b_(—)0, b_(—)1, . . . , b_M−1. L is thesize of modulation symbols. A modulation scheme is performed by changingthe amplitude and phase of a transmission signal. The modulation schemeincludes, for example, n-Phase Shift Keying (n-PSK) and n-QuadratureAmplitude Modulation (QAM) (where n is an integer of 2 or more).Specifically, the modulation scheme includes Binary PSK (BPSK),Quadrature PSK (QPSK), 8-PSK, QAM, 16-QAM, or 64-QAM.

A divider divides the modulation symbols c_(—)0, c_(—)1, . . . , c_L−1into slots. The order/pattern/scheme of dividing modulation symbols intoslots is not limited to a specific one. For instance, the divider maydivide the modulation symbols into slots, sequentially starting from thefirst modulation symbol (localized scheme). In this case, the modulationsymbols c_(—)0, c_(—)1, . . . , c_L/2−1 may be allocated to slot 0 andthe modulation symbols c_L/2, c_L/2+1, . . . , c_L−1 may be allocated toslot 1. When the modulation symbols are divided into slots, themodulation symbols may be interleaved (or permuted). For example,even-numbered modulation symbols may be allocated to slot 0 andodd-numbered modulation symbols may be allocated to slot 1. Themodulation process and the division process are interchangeable inorder.

A DFT precoder performs DFT precoding (e.g. 12-point DFT) with respectto the modulation symbols divided into the slots in order to generate asingle carrier waveform. Referring to FIG. 24, the modulation symbolsc_(—)0, c_(—)1, . . . , c_L/2−1 allocated to slot 0 are DFT-precoded toDFT symbols d_(—)0, d_(—)1, . . . , d_L/2−1 and the modulation symbolsc_L/2, c_L/2+1, . . . , c_L−1 allocated to slot 1 are DFT-precoded toDFT symbols d_L/2, d_L/2+1, . . . , d_L−1. DFT precoding may be replacedwith another linear operation (e.g. Walsh precoding).

A spreading block spreads the DFT-precoded signals at an SC-FDMA symbollevel (in the time domain). Time-domain spreading at the SC-FDMA symbollevel is performed using a spreading code (sequence). The spreading codeincludes a quasi-orthogonal code and an orthogonal code. Thequasi-orthogonal code includes, but is not limited to, a Pseudo Noise(PN) code. The orthogonal code includes, but is not limited to, a Walshcode and a DFT code. While the orthogonal code is described as a typicalexample of the spreading code for convenience of description, theorthogonal code may be replaced with the quasi-orthogonal code. Themaximum value of a spreading code size or an SF is limited by the numberof SC-FDMA symbols used for transmission of control information. Forexample, if four SC-FDMA symbols are used for control informationtransmission in one slot, an orthogonal code of length 4, w0, w1, w2, w3can be used in each slot. The SF means the degree of spreading ofcontrol information and may be related to the multiplexing order orantenna multiplexing order of a UE. The SF may be changed to 1, 2, 3, 4,. . . depending on system requirements. The SF may be predefined betweena BS and a UE or the BS may indicate an SF to the UE by DCI or RRCsignaling. For example, if one of SC-FDMA symbols for controlinformation is punctured to transmit an SRS, a spreading code with adecreased SF (e.g. SF=3 instead of SF=4) may be applied to the controlinformation in a corresponding slot.

A signal generated from the above operation is mapped to subcarriers ina PRB and converted into a time-domain signal by IFFT. A CP is added tothe time-domain signal and the generated SC-FDMA symbols are transmittedthrough an RF end.

Each operation will be described in more detail on the assumption thatACKs/NACKs are transmitted for five DL CCs. If each DL CC can transmittwo PDSCHs, ACK/NACK bits for the PDSCHs may be 12 bits, including a DTXstate. Under the assumption of QPSK and time spreading of SF=4, the sizeof a coding block (after rate matching) may be 48 bits. The coded bitsare modulated to 24 QPSK symbols and the QPSK symbols are divided intotwo slots each including 12 QPSK symbols. The 12 QPSK symbols in eachslot are converted into 12 DFT symbols by 12-point DFT. The 12 DFTsymbols in each slot are spread to four SC-FDMA symbols using aspreading code of SF=4 in the time domain and then mapped. Since 12 bitsare transmitted on [2 bits×12 subcarriers×8 SC-FDMA symbols], the codingrate is 0.0625 (=12/192). If SF=4, a maximum of four UEs may bemultiplexed per PRB.

FIG. 25 illustrates an exemplary structure of PUCCH format 3 using an OCof SF=5.

The basic signal processing operation is performed in the same manner asdescribed with reference to FIG. 25 except for the number and positionsof UCI SC-FDMA symbols and RS SC-FDMA symbols. A spreading block may beapplied in advance at the front end of the DFT precoder.

In FIG. 25, RSs may use the same structure as those used in the LTEsystem. For example, a base sequence may be cyclically shifted. Themultiplexing capacity of a data part is 5 due to SF=5. However, themultiplexing capacity of an RS part is determined by a CS intervalΔ_(shift) ^(PUCCH). For example, the multiplexing capacity may be12/Δ_(shift) ^(PUCCH). In this case, the multiplexing capacities for thecases in which Δ_(shift) ^(PUCCH)=1Δ_(shift) ^(PUCCH)=2, and Δ_(shift)^(PUCCH)=3 are 12, 6, and 4, respectively. In FIG. 25, while themultiplexing capacity of the data part is 5 due to SF=5, themultiplexing capacity of the RS part is 4 in case of Δ_(shift) ^(PUCCH).Therefore, overall multiplexing capacity may be limited to the smallerof the two values, 4.

FIG. 26 illustrates an exemplary structure of PUCCH format 3 that canincrease a multiplexing capacity at a slot level.

Overall multiplexing capacity can be increased by applying SC-FDMAsymbol-level spreading described with reference to FIGS. 24 and 25 toRSs. Referring to FIG. 26, the multiplexing capacity is doubled byapplying a Walsh cover (or a DFT code cover) within a slot. Then, themultiplexing capacity is 8 even in case of Δ_(shift) ^(PUCCH), therebypreventing the multiplexing capacity of a data part from decreasing. InFIG. 26, [y1 y2]=[1 1], [y1 y2]=[1 −1], or a linear transform thereof(e.g. [j j] [j −j], [1 j] [1 −j], etc.) may be used for an OC for RSs.

FIG. 27 illustrates an exemplary PUCCH format 3 structure that canincrease multiplexing capacity at a subframe level.

Without applying slot-level frequency hopping, the multiplexing capacityis doubled again by applying a Walsh cover in units of a slot. Asdescribed before, [x1 x2]=[1 1], [1 −1], or a transformation thereof maybe used as an OC.

For reference, the processing operation of PUCCH format 3 is not limitedto the orders illustrated in FIGS. 24 to 27.

Channel Selection

Channel selection refers to expression/transmission of specificinformation by selecting a specific resource from among a plurality ofresources. General channel selection is a scheme of transmittingspecific information by a combination of a resource and constellation.

Here, the resource may be specified by a physical time-frequencyresource and/or a sequence resource (e.g. a CS value). For example, inLTE release-8 PUCCH format 1/1a/1b, a specific resource may be selectedby a combination of an OC, a CS, and a Physical Resource Unit (PRU). Itmay be assumed that a plurality of resources on which channel selectionis performed is distinguished by a combination of the above threeresources. For example, a channel selection method shown in thefollowing Table 3 may be used.

TABLE 3 Ch1 Ch2 RS Data RS Data ACK a b 0 0 NACK 0 0 a b

In the above Table 3 and in the following description, values expressedas a, b, c, . . . may mean constellation values caused by modulation(e.g. BPSK, QPSK, etc.) in a channel Ch-x (x=1, 2, 3, . . . ).Alternatively, the values expressed as a, b, c, . . . may be valuesmultiplexed, scrambled, or covered by an allocated sequence or anallocated code, rather than the constellation values. Thus, the valuesexpressed as a, b, c, . . . with respect to Ch-x may be values capableof distinguishing therebetween and a method for distinguishing betweenthe values is not restricted. Notably, in the following description, thevalues expressed as a, b, c, . . . with respect to Ch-x are referred toas modulated values, for convenience of description.

In addition, the values expressed as a, b, c, . . . may be predeterminedspecific values rather than 0. For example, a may be ‘+1’ and b may be‘−1’.

In the example of Table 3, even if the same value is transmitted,different information (i.e. ACK or NACK) may be transmitted depending onwhich channel is used for transmission. For example, for ACKtransmission, a value a is transmitted in an RS part of resource 1 (i.e.Ch1) and a value b is transmitted in a data part of resource 1. For NACKtransmission, a is transmitted in an RS part of resource 2 (i.e. Ch2)and b is transmitted in a data part of resource 2. In this way, a methodfor transmitting different information depending on through whichresource a signal is transmitted may be referred to as channelselection.

In Table 3, a simple example without using complicated constellationmapping is shown but additional constellation mapping may be used totransmit more information. Table 4 shows an example using two types ofdistinguishable constellation mapping (e.g. BPSK).

TABLE 4 Ch1 Ch2 RS Data RS Data A/A a b 0 0 A/N a c 0 0 N/A 0 0 a b N/N0 0 a c

In the above Table 4, a, b, and c may be specific values other than 0.Notably, it is preferable that b and c be distant from each other onconstellation. For example, a may be used as ‘+1’ and b and c may beused as ‘+1’ and ‘−1’, respectively or ‘−1’ and ‘+1’, respectively. Inthe example of Table 4, a value modulated to b is transmitted inresource 1 (Ch1) for ACK/ACK transmission and a value modulated c istransmitted in resource 1 (Ch1) for ACK/NACK transmission. In addition,a value modulated to b is transmitted in resource 2 (Ch2) for NACK/ACKtransmission and a value modulated to c is transmitted in resource 2(Ch2) for NACK/NACK.

A mapping relationship for channel selection for ACK/NACK transmissionin TDD, used in legacy LTE release-8/9, is defined in Tables 5, 6, and 7shown below. In LTE release-8/9, TDD ACK/NACK multiplexing may have thesame meaning as TDD ACK/NACK channel selection but they have differentmeanings in a multicarrier support system (e.g. LTE-A or LTE-release-10)which will be described later.

In the following Tables 5, 6, and 7, a value M may be determined by a DLrelated set index K: k₀, k₁, . . . k_(M-1) (defined as in Table 12 whichwill be described later) in a TDD system. For example, if M=2 in Table5, two PUCCH resources n_(PUCCH,0) ⁽¹⁾ and n_(PUCCH,1) ⁽¹⁾ and a QPSKconstellation ‘b(0),b(1)’ in each PUCCH resource may be used to transmittwo types of ACK/NACK information including spatial bundling (i.e.ACK/NACK bundling for a plurality of codewords).

Specifically, the UE transmits bits ‘b(0),b(1)’ on an ACK/NACK resourcen_(PUCCH,1) ⁽¹⁾ using PUCCH format 1b in subframe n. The value‘b(0),b(1)’ and the ACK/NACK resource n_(PUCCH) ⁽¹⁾ may be generated bychannel selection according to the following Tables 5, 6, and 7. Tables5, 6, and 7 show ACK/NACK multiplexing transmission when M=2, M=3, andM=4, respectively. If ‘b(0),b(1)’ is mapped to NACK/ACK, the UE does nottransmit an ACK/NACK response in subframe n.

TABLE 5 HARQ-ACK(0), HARQ-ACK(1) n_(PUCCH) ⁽¹⁾ b(0), b(1) ACK, ACKn_(PUCCH,1) ⁽¹⁾ 1, 1 ACK, NACK/DTX n_(PUCCH,0) ⁽¹⁾ 0, 1 NACK/DTX, ACKn_(PUCCH,1) ⁽¹⁾ 0, 0 NACK/DTX, NACK n_(PUCCH,1) ⁽¹⁾ 1, 0 NACK, DTXn_(PUCCH,0) ⁽¹⁾ 1, 0 DTX, DTX N/A N/A

TABLE 6 HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2) n_(PUCCH) ⁽¹⁾ b(0), b(1)ACK, ACK, ACK n_(PUCCH,2) ⁽¹⁾ 1, 1 ACK, ACK, NACK/DTX n_(PUCCH,1) ⁽¹⁾ 1,1 ACK, NACK/DTX, ACK n_(PUCCH,0) ⁽¹⁾ 1, 1 ACK, NACK/DTX, NACK/DTXn_(PUCCH,0) ⁽¹⁾ 0, 1 NACK/DTX, ACK, ACK n_(PUCCH,2) ⁽¹⁾ 1, 0 NACK/DTX,ACK, NACK/DTX n_(PUCCH,1) ⁽¹⁾ 0, 0 NACK/DTX, NACK/DTX, ACK n_(PUCCH,2)⁽¹⁾ 0, 0 DTX, DTX, NACK n_(PUCCH,2) ⁽¹⁾ 0, 1 DTX, NACK, NACK/DTXn_(PUCCH,1) ⁽¹⁾ 1, 0 NACK, NACK/DTX, NACK/DTX n_(PUCCH,0) ⁽¹⁾ 1, 0 DTX,DTX, DTX N/A N/A

TABLE 7 HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2), HARQ-ACK(3) n_(PUCCH) ⁽¹⁾b(0), b(1) ACK, ACK, ACK, ACK n_(PUCCH,1) ⁽¹⁾ 1, 1 ACK, ACK, ACK,NACK/DTX n_(PUCCH,1) ⁽¹⁾ 1, 0 NACK/DTX, NACK/DTX, NACK, DTX n_(PUCCH,2)⁽¹⁾ 1, 1 ACK, ACK, NACK/DTX, ACK n_(PUCCH,1) ⁽¹⁾ 1, 0 NACK, DTX, DTX,DTX n_(PUCCH,0) ⁽¹⁾ 1, 0 ACK, ACK, NACK/DTX, NACK/DTX n_(PUCCH,1) ⁽¹⁾ 1,0 ACK, NACK/DTX, ACK, ACK n_(PUCCH,3) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX,NACK/DTX, n_(PUCCH,3) ⁽¹⁾ 1, 1 NACK ACK, NACK/DTX, ACK, NACK/DTXn_(PUCCH,2) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, ACK n_(PUCCH,0) ⁽¹⁾ 0, 1ACK, NACK/DTX, NACK/DTX, NACK/DTX n_(PUCCH,0) ⁽¹⁾ 1, 1 NACK/DTX, ACK,ACK, ACK n_(PUCCH,3) ⁽¹⁾ 0, 1 NACK/DTX, NACK, DTX, DTX n_(PUCCH,1) ⁽¹⁾0, 0 NACK/DTX, ACK, ACK, NACK/DTX n_(PUCCH,2) ⁽¹⁾ 1, 0 NACK/DTX, ACK,NACK/DTX, ACK n_(PUCCH,3) ⁽¹⁾ 1, 0 NACK/DTX, ACK, NACK/DTX, NACK/DTXn_(PUCCH,1) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, ACK n_(PUCCH,3) ⁽¹⁾ 0, 1NACK/DTX, NACK/DTX, ACK, NACK/DTX n_(PUCCH,2) ⁽¹⁾ 0, 0 NACK/DTX,NACK/DTX, NACK/DTX, ACK n_(PUCCH,3) ⁽¹⁾ 0, 0 DTX, DTX, DTX, DTX N/A N/A

In Tables 5, 6, and 7, HARQ-ACK(i) indicates a HARQ ACK/NACK/DTX resultfor an i-th data unit (0≦i≦3). DTX means that there is no data unittransmitted for corresponding HARQ-ACK(i) or the data unit correspondingto HARQ-ACK(i) has not been detected by the UE. In this specification,HARQ-ACK is used interchangeably with ACK/NACK. A maximum of four PUCCHresources (i.e. n⁽¹⁾ _(PUCCH,0) to n⁽¹⁾ _(PUCCH,3)) may be occupied foreach data unit. Multiplexed ACK/NACK signals are transmitted through onePUCCH resource selected from among the occupied PUCCH resources. InTables 5, 6, and 7, n⁽¹⁾ _(PUCCH,x) indicates a PUCCH resource used foractual ACK/NACK transmission, and ‘b(0)b(1)’ indicates two bitstransmitted through the selected PUCCH resource, which is modulatedusing QPSK. For example, if the UE successfully decodes four data unitsas in Table 7, the UE transmits (1, 1) to the BS through a PUCCHresource connected to n⁽¹⁾ _(PUCCH,1). Since combinations of PUCCHresources and QPSK symbols cannot represent all of available ACK/NACK,NACK and DTX are coupled (expressed as NACK/DTX) except in some cases.

Meanwhile, in an LTE-A (or LTE release-10) system to which the presentinvention is applied, there are no particular restrictions as to achannel selection mapping relationship which is used to apply thechannel selection method. For example, a channel selection mappingrelationship for transmitting ACK/NACK information as shown in Tables 8to 10 may be defined. Table 8 defines a mapping relationship for 2-bitACK/NACK, Table 9 defines mapping relationship for 3-bit ACK/NACK, andTable 10 defines a mapping relationship for 4-bit ACK/NACK.

TABLE 8 ACK/NACK resource A/N state 1 2 A, A −1 A, N/D −1 N/D, A +1 N,N/D +1 D, N/D No transmission

TABLE 9 ACK/NACK resource A/N state 1 2 3 A, A, A −1 A, N/D, A +j N/D,A, A −j N/D, N/D, A −1 A, A, N/D −1 A, N/D, N/D +j N/D, A, N/D −j N/D,N/D, N +1 N/D, N/D, D +1 (except for D, D, D) D, D, D No transmission

TABLE 10 ACK/NACK resource A/N state 1 2 3 4 A, A, A, A −1 A, N/D, A, A−j N/D, A, A, A −j N/D, N/D, A, A −1 A, A, A, N/D +j A, N/D, A, N/D +1N/D, A, A, N/D +1 N/D, N/D, A, N/D +j A, A, N/D, A −1 A, N/D, N/D, A +jN/D, A, N/D, A −j N/D, N/D, N/D, A +1 A, A, N/D, N/D −1 A, N/D, N/D, N/D+j N/D, A, N/D, N/D −j N/D, N/D, N/D, N/D +1 (except for D, D, N/D, N/D)D, D, N/D, N/D No transmission

Alternatively, channel mapping relationships for 1-bit to 4-bit ACK/NACKas shown in Table 11 may be defined. In the example of Table 11, onechannel resource h0 and constellation values 1 and −1 generated by datamodulation may be used to transmit 1-bit ACK/NACK information. Fortransmission of 2-bit ACK/NACK information, two channel resources h0 andh1 and constellation values 1, −1, −j, and j are used. For 3-bitACK/NACK information, three channel resources h0, h1, and h2 andconstellation values 1, −1, −j, and j generated by data modulation areused. Four channel resources h0, h1, h2, and h3 and constellation values1, −1, −j, and j generated by data modulation may be used to transmit4-bit ACK/NACK information.

TABLE 11

UL ACK/NACK to DL Transmission in Multicarrier Support System

In a multicarrier system or a CA support system, DL resources may bedefined as a DL CC and UL resources may be defined as a UL CC. Inaddition, a combination of DL resources and UL resources may be referredto as a cell. If DL CCs and UL CCs are asymmetrically configured, thecell may refer to only the DL CCs (or UL CCs). For example, if aspecific UE is configured with one serving cell, one DL CC and one UL CCare present. However, if a specific UE is configured with two or moreserving cells, DL CCs which is equals in number to the cells and UL CCswhich is equal to or less than the DL CCs in number are present. When aspecific UE is configured with a plurality of serving cells, amulticarrier environment in which the number of UL CCs is greater thanthe number of DL CCs may be supported.

Linkage between carrier frequencies (center frequencies of a cell) ofthe DL and UL resources may be indicated by system informationtransmitted on the DL resources. For example, a combination of the DLresources and the UL resources may be configured by linkage defined byan SIB2.

According to the above definition, CA may refer to an aggregate of twoor more cells having different carrier frequencies. That is, the case inwhich a specific UE is configured with two or more serving cells havingdifferent carrier frequencies may be referred to as a CA environment.For UEs supporting CA, one or more SCells may be aggregated with a PCellto support increased bandwidth.

In this case, the serving cell may be a PCell or an SCell. For a UE thatis in an RRC_CONNECTED state without supporting CA, only one servingcell including a PCell is present. Meanwhile, for a UE in anRRC_CONNECTED state, for which CA is configured, serving cells refer toa set of one or more cells including a PCell and SCells.

The PCell is a central cell of control related communication amongserving cells configured in a CA environment. The PCell is a cellindicated or used by a UE in an initial connection establishmentprocedure, a connection re-establishment procedure, or a handoverprocedure. In LTE-A release 10, the UE may receive and transmit a PUCCHonly on the PCell thereof. In future releases, PUCCH transmission on theSCell of the UE may be permitted. In addition, the UE may perform amonitoring procedure for system information acquisition and change onlyon the PCell. For a CA support UE, a BS may change only through ahandover procedure using an RRCConnectionReconfiguration messageincluding mobilityControlInfo.

Next, SCells refer to cells except for the PCell among serving cellsconfigured in a CA environment. In LTE-A release 10, no PUCCHs arepresent on the SCell. If an SCell is added, the BS may provide allsystem information related to an operation on the SCell of anRRC_CONNECTED state to the UE supporting CA through dedicated signaling.For the SCell, change in system information may be performed by releaseand addition of the SCell through one RRCConnectionReconfigurationmessage. The BS may transmit dedicated signaling having a differentparameter from a parameter included in a broadcast message on the SCellto the UE. After an initial security activation procedure, the BS mayconfigure one or more SCells in addition to the PCell (a cell configuredas a serving cell during a connection establishment procedure) for theUE. The PCell may be used to provide security input and higher-layersystem information and the SCell may be used to provide additional DLresources and, when necessary, UL resources. The BS may independentlyadd, eliminate, or correct the SCell through an RRC reconnectionreconfiguration procedure using an RRCConnectionReconfiguration messagewhich includes or does not include mobilityControlInfo.

In the CA environment, PhyCellId, SCellIndex, and ServCellIndex may bedefined as RRC related parameters/Information Elements (IEs). PhyCellIdmay have an integer ranging from 0 to 503 and may be used as a physicallayer identifier of a cell. SCellIndex may have an integer ranging from1 to 7 and may be used as an identifier of an SCell. ServCellIndex mayhave an integer ranging from 0 to 7 and may be used as an identifier ofa serving cell (PCell or SCell). ServCellIndex having a value of 0 maybe applied to the PCell and, for the SCell, SCellIndex may be applied.That is, a cell having the smallest (or lowest) cell index inServCellIndex may be defined as the PCell.

In summary, multiple carriers in CA are divided into a PCell and anSCell which are UE-specific parameters. A specific UE may have one ormore configured serving cells. If a plurality of configured servingcells is present, a cell having the smallest ServCellIndex among thecells is a PCell and the other cells are SCells. In LTE-A release 10, ifthe UE has a plurality of configured serving cells in TDD, UL-DLconfigurations constituting a UL subframe and a DL subframe in a framemay be equal in all cells and HARQ-ACK timings indicating which ULsubframe is used to transmit ACK/NACK for a PDSCH transmitted in aspecific DL subframe according to the UL-DL configuration may be equalin all cells. In future releases, if the UE has a plurality ofconfigured serving cells in TDD, the UL-DL configurations may differbetween cells and the HARQ-ACK timings according to the UL-DLconfigurations may differ between cells.

In addition, the UE may transmit UCI such as CSI (including CQI, RI,PMI, etc.) and HARQ ACK/NACK, measured from one or more CCs, to the BSin one predetermined CC. For example, if a plurality of ACK/NACKfeedbacks is needed, the UE may gather the ACK/NACK feedbacks (e.g.ACK/NACK multiplexing or ACK/NACK bundling) received from a PCell DL CCand SCell DL CC(s) and may transmit the gathered ACK/NACK feedbacks tothe BS in a UL CC of the PCell using one PUCCH.

In the present invention, when a plurality of ACK/NACK signals for aplurality of DL transmissions is transmitted through one PUCCH, a unit(one or more subframes and/or one or more carriers) constituting theplurality of DL transmissions is referred to as a bundling window. Thatis, time domain bundling refers to bundling ACK/NACK signals for DLtransmissions in a plurality of subframes. CC domain bundling refers tobundling ACK/NACK signals for DL transmissions in a plurality of CCs.Time domain/CC domain bundling refers to bundling ACK/NACK signals forDL transmissions in a plurality of subframes and a plurality of CCs.Although ACK/NACK bundling may be performed by logical AND operation,the present invention is not limited thereto and other operations suchas logical OR may be used.

In addition, a unit for actually performing time domain bundling and/orCC domain bundling using a logical AND (or logical OR) operation may bereferred to as a real bundling window. That is, one or more realbundling windows may be present in one bundling window. In other words,the size of a bundling window is equal to or greater than the size of areal bundling window. Here, spatial bundling for a plurality of ACK/NACKbits for one DL transmission (i.e. ACK/NACK bundling for a plurality ofcodewords) may be applied regardless of the bundling window or the realbundling window.

Examples in which ACK/NACK for DL transmission is needed, defined in the3GPP LTE system, will now be described. Here, when ACK/NACK istransmitted in subframe n, the ACK/NACK relates to DL transmission insubframe n-k.

In a TDD system, a DL related set index K: k₀, k₁, . . . k_(M-1) may begiven per UL-DL configuration of Table 1 as shown in Table 12 withrespect to the relationship between subframe n and subframe n-k.

TABLE 12 UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4— — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4,6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 —— — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 —— 7 7 —

In FDD, M is always 1 and K always satisfies {k₀}={4}. When ACK/NACK forDL transmission in subframe n-k is transmitted in subframe n, the DLtransmission in subframe n-k may correspond to one or more of thefollowing three cases.

Case 1 is when ACK/NACK feedback for a PDSCH(s) indicated by a PDCCH(s)detected in a subframe(s) n-k is needed. Here, kεK, and K variesaccording to subframe index n and UL-DL configuration and includes Melements {k₀, k₁, . . . k_(M-1)}. The following Table 12 shows K: {k₀,k₁, . . . k_(M-1)}. Case 1 relates to a PDSCH(s) requiring generalACK/NACK feedback. In the following description, Case 1 is referred toas ‘ACK/NACK for a PDSCH’ or ‘ACK/NACK for a PDSCH with a PDCCH’.

Case 2 is when ACK/NACK feedback for a PDCCH(s) indicating DL SPSrelease in a subframe(s) n-k is needed. Here, kεK and K denotes the sameindex as in the description given in Case 1. ACK/NACK of Case 2 meansACK/NACK feedback for a PDCCH(s) for SPS release. Meanwhile, whileACK/NACK feedback for DL SPS release is performed, ACK/NACK feedback fora PDCCH(s) indicating SPS activation is not performed. In the followingdescription, Case 2 is referred to as ‘ACK/NACK for DL SPS releasePDCCH’.

Case 3 is when ACK/NACK feedback for transmission of a PDSCH(s) withoutcorresponding a PDCCH(s) detected in subframe(s) n-k is needed. Here,kεK and K denotes the same index as in description given in Case 1. Case3 relates to PDSCHs without PDCCHs and means ACK/NACK feedbacks forPDSCHs allocated by SPS. In the following description, Case 3 isreferred to as ‘ACK/NACK for DL SPS PDSCH’.

In the following description, a PDSCH with a corresponding PDCCH, aPDSCH for DL SPS release, and a PDSCH without a corresponding PDCCH arecollectively referred to as DL transmission requiring ACK/NACKtransmission.

Examples of the present invention when the above ACK/NACK for DLtransmission is applied to a multicarrier system will be describedhereinbelow in detail.

For convenience of description, the examples of the present inventionwill be described under the following assumptions. However, theembodiments of the present invention are not limited to the followingassumptions.

(1) One PCell and one or more SCells may be present.

(2) A PDSCH with a corresponding PDCCH may be present on a PCell and anSCell(s).

(3) A PDCCH indicating DL SPS release may be present only on a PCell.

(4) A PDSCH without a corresponding PDCCH (=SPS PDSCH) may be presentonly on a PCell.

(5) Cross-scheduling from a PCell to a SCell(s) may be supported.

(6) Cross-scheduling from an SCell(s) to a PCell is not supported.

(7) Cross-scheduling from an SCell(s) to another SCell (or other SCells)may be supported.

In description of the present invention, time-domain bundling and/orCC-domain bundling means a logical AND operation. However, time-domainbundling and/or CC-domain bundling may be performed through othermethods such as a logic OR operation, etc. That is, time-domain bundlingor CC-domain bundling refers to a method for expressing a plurality ofACKs/NACKs over a plurality of subframes or CCs as ACK/NACK informationhaving less bits, in an ACK/NACK response using a single PUCCH format.In other words, time domain bundling or CC domain bundling refers to anarbitrary method for expressing M-bit ACK/NACK information as N bits(M≧N).

In a system to which multiple carriers and/or TDD are applied, aplurality of ACK/NACK bits may be transmitted by channel selection usingPUCCH format 1a/1b, PUCCH format 3, or channel selection using PUCCHformat 3. For PUCCH resource indexes for the PUCCH formats, implicitmapping, explicit mapping, or a composite of implicit and explicitmapping may be used. Implicit mapping may use a method for deriving aPUCCH resource index based on the lowest CCE index of a correspondingPDCCH. Explicit mapping may use a method for indicating or deriving thePUCCH resource index among sets predetermined by RRC configuration by anACK/NACK Resource Indicator (ARI) in the PDCCH.

In relation to the present invention, when a new format (e.g. PUCCHformat 3 described with reference to FIGS. 24 to 27) for transmitting aplurality of ACK/NACK bits, resource allocation of PUCCH format 3 isbasically performed based on explicit resource allocation.

Specifically, a UE configured as PUCCH format 3 may be explicitly (e.g.through RRC signaling) assigned an orthogonal resource for the format.In addition, a final PUCCH resource may be determined by an ARI value ina DCI format in a PDCCH for a PDSCH transmitted on the SCell amongorthogonal resources predetermined by RRC configuration. In this case,the ARI may be used as an offset based on an explicitly signaled PUCCHresource value or may be used to indicate which one among one or morePUCCH resource sets is to be used.

To contain ARI information in a PDCCH, a method of reusing a fielddefined in a DCI format of an existing PDCCH for an ARI purpose may beconsidered. The PDCCH may include a Transmit Power Control (TPC) field.An original purpose of the TPC field is to control transmit power of aPUCCH and/or a PUSCH and may consist of 2 bits.

As described above, when the ARI is transmitted only on the SCell, a TPCfield in the PDCCH on the SCell may be reused as the ART. Meanwhile, theTPC field in the PDCCH on the PCell may be used for transmit powercontrol of a PUCCH and/or a PUSCH.

In the LTE release-10 system, since a PDCCH for scheduling a PDSCH of aPCell cannot be received on an SCell (i.e. cross-carrier scheduling ofthe PDSCH of the PCell from the PDCCH of the SCell is not permitted),the meaning that the UE receives the PDSCH only on the PCell may beequivalent to the meaning that the UE receives the PDCCH only on thePCell.

Explicit ACK/NACK resource allocation configured by RRC signaling may beperformed as follows.

First, a PDCCH corresponding to a PDSCH on an SCell (i.e. a PDCCH forscheduling a PDSCH) may include information (e.g. ARI) for deriving aspecific PUCCH resource from an RRC-configured resource(s).

Next, if a PDCCH corresponding to a PDSCH is not received on an SCelland the PDSCH is received only on a PCell, one of the following casesmay be applied. First, a PUCCH resource (i.e. PUCCH format 1a/1b)defined in LTE release-8 may be used. Second, a PDCCH corresponding to aPDSCH on the PCell may include information (e.g. ARI) for deriving aspecific PUCCH resource from an RRC-configured resource(s).

The UE may assume that all PDCCHs corresponding to PDSCHs on SCells havethe same ARI.

In this way, when ARI information is defined to be transmitted only onthe SCells, if the UE receives only a PDSCH(s) for the PCell (orreceives a PDCCH(s) only on the PCell) in a multicarrier and/or TDDsystem, since the UE is unable to know ARI information transmitted fromthe SCell, a final resource index for a PUCCH format (PUCCH format 3) tobe used by the UE cannot be determined.

The present invention devised to solve the above problem proposesmethods for determining a final resource index for a PUCCH format evenwhen the UE receives only a PDSCH(s) for a PCell (or receives a PDCCH(s)only on the PCell).

In various examples of the present invention, the case in which a UEreceives only a PDSCH(s) for a PCell (or the case in which the UEreceives a PDCCH(s) only on the PCell) is briefly referred to as a‘PCell-only-receiving’, for convenience of description. Here,PCell-only-receiving is defined in terms of reception of the UE. If thepresent invention is applied to a multicarrier environment, the UE mayhave one configured cell or a plurality of configured cells. If the UEhas one configured cell, the cell may be a PCell and if the UE has aplurality of configured cells, the cells may be comprised of one PCelland one or more SCells. The present invention may be applied to one ofthe two cases or to both cases. Namely, the PCell-only-receiving casemay be applied to both a CA environment and a non-CA environment.

Moreover, as described previously, a new PUCCH format, i.e. PUCCH format3, may be used for ACK/NACK transmission for DL transmission receivedthrough a plurality of DL subframes in a TDD system even when the UEincludes one configured cell. PUCCH format 3 may also be used in an FDDor TDD system when the UE includes a plurality of configured cells. Thatis, PUCCH format 3 may be used in a CA system or non-CA TDD system.

Further, in various examples of the present invention, a candidate setof resources used for PUCCH format 3 may be RRC-configured. A specificPUCCH resource in the PUCCH resource candidate set may be determined byor derived from a value of ARI information (which may expressed as reuseof a TPC field of a PDCCH). In brief, a PUCCH format 3 resource to beused by the UE is derived from an ARI included in a PDCCH amongRRC-configured resource candidates. The ARI has a size of X bits and Xmay be defined as 2 when the ARI is expressed by reuse of the TPC field(of 2 bits in size) of the PDCCH on the SCell as described above. Forexample, one resource of four PUCCH resource candidates may be expressedusing a 2-bit ARI.

The present invention is described on the assumption that transmissionis performed through a single antenna requiring one orthogonal resource,for convenience of description associated with application of PUCCHformat 3. However, it is apparent that the present invention is notlimited thereto and the principle of the present invention is applicablein the same manner even when a multi-antenna transmit diversity schemesuch as Spatial Orthogonal-Resource Transmit Diversity (SORTD) isapplied to PUCCH format 3.

An exemplary assumption of the present invention for PUCCH format 3resource allocation will now be described based on the abovedescription.

A resource for PUCCH format 3 may be expressed as n_(PUCCH) ³ and fourorthogonal resource candidates for PUCCH format 3 may be expressed asn_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, and n_(PUCCH,3) ³. Anarbitrary UE may be assigned such four orthogonal resources through RRCsignaling. RRC signaling may be, for example, four separate RRC signals.UE may be informed of one set n_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2)³, n_(PUCCH,3) ³ consisting of four orthogonal resources through one RRCsignaling. The UE that has been assigned the four PUCCH resourcecandidates may finally determine one PUCCH resource (n_(PUCCH) ³) amongthe four PUCCH resource candidates based on a value indicated by anadditionally received ARI.

The following Table 13 shows exemplary resource allocation for PUCCHformat 3 in single-antenna transmission.

TABLE 13 Value of ARI (or TPC command for PUCCH on SCells) n_(PUCCH) ³‘00’ The first PUCCH resource index (n_(PUCCH,0) ³) configured by thehigher layers ‘01’ The second PUCCH resource index (n_(PUCCH,1) ³)configured by the higher layers ‘10’ The third PUCCH resource index(n_(PUCCH,2) ³) configured by the higher layers ‘11’ The fourth PUCCHresource index (n_(PUCCH,3) ³) configured by the higher layers

Hereinafter, various embodiments of the present invention will bedescribed in detail based on the above description.

Embodiment 1

The present embodiment 1 relates to a method of using predefinedresource allocation in a PCell-only-receiving case (i.e. the case ofreceiving only a PDSCH(s) for a PCell or the case of receiving aPDCCH(s) only on the PCell).

In the PCell-only-receiving case, it is possible to predetermine aresource index of PUCCH format 3. That is, in a non-PCell-only-receivingcase, the UE may derive a PUCCH resource index from an ARI received onan SCell, whereas in the PCell-only-receiving, the UE may use apredetermined PUCCH resource index.

Specifically, a new index may be predetermined so that the UE candetermine a PUCCH format 3 resource to be used in thePCell-only-receiving case. The new index may have the same meaning asthe ARI on the SCell. In other words, the index may be used to indicateany one of resource candidate sets configured through RRC signaling. Theindex may be defined in the form of a predefined rule (or a specificvalue) indicating a resource of a specific order (e.g. the firstresource or last resource) among the resource candidate sets.

For example, in the PCell-only-receiving case, the index capable ofdetermining the PUCCH format 3 resource may be defined as asystem-specific value. Alternatively, the index may be RRC-configured asan eNB-specific value or as a UE-specific value.

FIG. 28 is a flowchart illustrating predefined resource allocation forPUCCH resource determination in a PCell-only-receiving case.

In step S2810, a UE may receive a PUCCH resource candidate setn_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, n_(PUCCH,3) ³ includingfour resources for PUCCH format 3 through higher-layer configuration(e.g. RRC signaling).

In step S2820, when PUCCH format 3 is used for ACK/NACK transmission,the UE may determine whether a situation is a PCell-only-receiving case.If a determination result in step S2820 is NO (i.e. anon-PCell-only-receiving case), step S2830 is performed and if YES (i.e.a PCell-only-receiving case), step S2840 is performed.

In step S2830, the UE may calculate/select one PUCCH resource (i.e. oneresource index) to be used thereby from the four PUCCH resourcecandidates using an ARI indicated by reuse of a TPC field in a PDCCH(s)of an SCell.

Meanwhile, since a PDCCH is not received on the SCell in step S2840, theUE may select one PUCCH resource from among the four PUCCH resourcecandidates according to a predefined rule (or a predefined index). Inthe illustrated example of FIG. 28, the predefined rule is to select thelast PUCCH resource index in the PUCCH resource candidate set. That is,in step S2840, the UE may calculate/select n_(PUCCH,3) ³.

After step S2830 or step S2840, the UE may transmit ACK/NACK informationthrough PUCCH format 3 using a resource corresponding to thecalculated/selected index.

Embodiment 2

The present embodiment 2 relates to a method for predetermining anadditional resource index and using the additional resource index forPUCCH resource allocation in a PCell-only-receiving case (i.e. the caseof receiving only a PDSCH(s) for a PCell or the case of receiving aPDCCH(s) only on the PCell).

In the PCell-only-receiving case, it is possible to predetermine anadditional resource index of PUCCH format 3. That is, the UE may derivea PUCCH resource index from an ARI received on an SCell in anon-PCell-only-receiving case, whereas the UE may use a predeterminedadditional PUCCH resource index in the PCell-only-receiving case. Thepredetermined index in the above Embodiment 1 is a predetermined indexfor one of the PUCCH resource candidates configured for the UE andEmbodiment 2 is different from Embodiment 1 in that the additionalresource index separate from the PUCCH resource candidates configuredfor the UE is predetermined.

According to this embodiment, for example, if a 2-bit ARI is used and aset of four RRC-configured resource candidates is defined, oneadditional resource candidate may be signaled to the UE through RRCsignaling. Then, an RRC-configured resource candidate set includes fivePUCCH resource indexes and one predetermined resource index (e.g. thelast index) thereamong may be defined as being used only in thePCell-only-receiving case. Alternatively, one resource candidate forPCell-only-receiving may be defined separately from the four PUCCHresource candidates. In both of the above two cases, a reserved resourceindex for only the PCell-only-receiving case (i.e. a resource indexwhich is not designated by an ARI on an SCell) may be allocated to theUE. Here, while it is preferable not to overlap one additional resourcecandidate for PCell-only-receiving with the four existing RRC-configuredresource candidates, overlapping may be permitted in some cases.

FIG. 29 is a flowchart illustrating additional predefined resourceallocation for PUCCH resource determination in a PCell-only-receivingcase

In step S2910, a UE may receive a PUCCH resource candidate set{n_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, n_(PUCCH,3) ³, n_(PUCCH,4)⁽³⁾} including four resources for PUCCH format 3 through higher-layerconfiguration (e.g. RRC signaling).

In step S2920, when PUCCH format 3 is used for ACK/NACK transmission,the UE may determine whether a situation is a PCell-only-receiving case.If a determination result in step S2920 is NO (i.e. anon-PCell-only-receiving case), step S2830 is performed and if YES (i.e.a PCell-only-receiving case), step S2940 is performed.

In step S2930, the UE may calculate/select one PUCCH resource to be usedthereby from among four PUCCH resource candidates (n_(PUCCH,0) ³,n_(PUCCH,1) ³, n_(PUCCH,2) ³, n_(PUCCH,3) ³) using an ARI indicated byreuse of a TPC field in a PDCCH(s) of an SCell, among four PUCCHresource candidates (e.g. four low-index PUCCH resources n_(PUCCH,0) ³,n_(PUCCH,1) ³, n_(PUCCH,2) ³, and n_(PUCCH,3) ³) which are predeterminedaccording to a prescribed rule from the five PUCCH resource candidates.

Meanwhile, since a PDCCH is not received on the SCell in step S2940, theUE may select one PUCCH resource according to a predefined rule. Thepredefined rule may be a rule for selecting the last resourcen_(PUCCH,4) ⁽³⁾ from among the five RRC-configured PUCCH resourcecandidates. It may be defined not to overlap the rule for determiningfour among five PUCCH resource candidates in step S2930 with the rulefor determining one among five PUCCH resource candidates in step S2940.However, in some cases, a rule may be defined such that an overlappedresource candidate is selected.

After step S2930 or step S2940, the UE may transmit ACK/NACK informationthrough PUCCH format 3 using a resource corresponding to thecalculated/selected index.

Embodiment 3

Embodiment 3 relates to a method of using a Downlink Assignment Index(DAI) for PUCCH resource allocation in a PCell-only-receiving case (i.e.the case of receiving only a PDSCH(s) for a PCell or the case ofreceiving a PDCCH(s) only on the PCell).

In the above-described Embodiments 1 and 2, the methods for deriving aresource index for PUCCH format 3 in PCell-only-receiving withoutadditional physical layer signaling (e.g. PDCCH signaling) has beendescribed. Embodiment 3 relates to a method defining and usinginformation capable of performing the function of the ARI among physicallayer signals received on a PCell, although the ARI cannot be receivedon an SCell as in an existing scheme due to absence of a PDCCH on theSCell. Specifically, this embodiment relates to a method of using DAIinformation included in a PDCCH as ARI information in thePCell-only-receiving case.

A DAI field in the PDCCH is defined in a TDD system and a DAI isassigned with respect to DL allocation (or PDSCH scheduling). When theUE transmits ACK/NACK signals for multiple DL assignments (PDSCHs) inone UL subframe, information about the number of DL assignments (PDSCHs)for which ACK/NACK signals are to be transmitted may be derived from theDAI. For example, when the UE transmits ACK/NACK signals (using ACK/NACKbundling) for multiple DL assignments (PDSCHs) to a BS, the case inwhich the UE fails to receive (i.e. miss) a part of multiple PDCCHs mayoccur. At this time, since the UE cannot be aware of the fact that aPDSCH corresponding to a reception-failed PDCCH has been transmittedthereto, an error may occur in ACK/NACK generation. Such a problem maybe solved using the DAI. In an existing TDD system, for example, in thecase in which one UL subframe corresponds to N DL subframes, if DAIs aresequentially assigned (i.e. sequentially counted) to PDCCHs transmittedin the N DL subframes, the UE is able to know whether previous PDCCHshave been correctly received through DAI information in the PDCCH.

In this embodiment, it is proposed to reuse a DAI as an ARI fordetermining PUCCH resource assignment in consideration of the case inwhich the DAI in the PDCCH of a PCell is not used for an originalpurpose when PUCCH format 3 is used. Specifically, even though PUCCHformat 3 is used in the TDD system, DAI information is not needed inoperation as ACK/NACK full multiplexing mode in which time-domainbundling or CC-domain (or frequency-domain) bundling is not performed.Accordingly, the DAI field may be reused as the ARI forPCell-only-receiving.

FIG. 30 is a flowchart illustrating an example of using a DAI field asan ARI for PUCCH resource determination in a PCell-only-receiving case.

In step S3010, a UE may receive a PUCCH resource candidate setn_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, n_(PUCCH,3) ³ includingfour resources for PUCCH format 3 through higher-layer configuration(e.g. RRC signaling).

In step S3020, when PUCCH format 3 is used for ACK/NACK transmission,the UE may determine whether a situation is a PCell-only-receiving case.If the determination result in step S3020 is NO (i.e. anon-PCell-only-receiving case), step S3030 is performed and if YES (i.e.a PCell-only-receiving case), step S3040 is performed.

In step S3030, the UE may calculate/select one PUCCH resource (i.e. oneresource index) to be used thereby from among the four PUCCH resourcecandidates using an ARI indicated by reuse of a TPC field in a PDCCH(s)of an SCell.

Meanwhile, in step S3040, since the PDCCH is not received on the SCell,the UE may select one PUCCH resource (i.e. one resource index) to beused thereby from among the four PUCCH resource candidates using an ARIindicated by reuse of the DAI field in a PDCCH of a PCell.

After step S3030 or step S3040, the UE may transmit ACK/NACK informationthrough PUCCH format using a resource corresponding to thecalculated/selected index.

Embodiment 3-1

Embodiment 3-1 relates to an example of applying the same ARI value inbundling subframes in a PCell-only-receiving case (i.e. the case ofreceiving only a PDSCH(s) for a PCell or the case of receiving aPDCCH(s) only on the PCell).

The term bundling subframes (or bundling window) used in description ofthe present invention means one unit consisting of DL subframes whenACK/NACK responses for the DL subframes in a bundling window aretransmitted through one UL PUCCH, rather than a unit of reallyperforming bundling in the time domain or CC domain (or frequencydomain).

For instance, in an LTE release-8 TDD system, a definition as to whichprevious DL subframe(s) (subframe n-k) are used to transmit an ACK/NACKresponse to DL transmissions in a specific UL subframe (subframe n) isgiven as shown in the above Table 12 (showing a DL related set index K:k₀, k₁, . . . k_(M-1)). In describing bundling subframes by way ofexample of Table 12, when an ACK/NACK response to DL transmission in aspecific DL subframe(s) is transmitted in a specific UL subframe, thespecific DL subframe(s) are referred to as bundling subframes. Forexample, in UL-DL configuration 4, bundling subframes for UL subframe 2are DL subframes 12, 8, 7, and 11 and bundling subframes for UL subframe3 are DL subframes 6, 5, 4, and 7.

If PUCCH format 3 is used in TDD, ACK/NACK responses to DL transmissionsin multiple DL subframes may be transmitted through one UL PUCCH asdescribed previously. Here, when one or more PDCCHs are detected inmultiple DL subframes in a PCell-only-receiving case according toEmbodiment 3, if ARI (or DAI) values indicated by the respective PDCCHsare different, it is unclear which ARI value is used to calculate/selecta PUCCH resource.

To prevent this problem, the ARI values (i.e. values of the DAI fields)of PDCCHs transmitted on the PCell in bundling subframes should beidentically maintained.

Embodiment 3-2

Embodiment 3-2 relates to an example of applying the same ARI value inbundled CCs. This embodiment may also be applied to aPCell-only-receiving case which may include the case in which a UEcannot detect DL transmission on an SCell(s) and receives DLtransmission only on a PCell although a BS has performed DL transmissionon the PCell and SCell(s).

The term bundling subframes (or bundling window) used in description ofthe present invention means one unit consisting of DL CCs when ACK/NACKresponses to the DL CCs in a bundling window are transmitted through oneUL PUCCH irrespective of presence/absence of bundling, rather than aunit of actually performing bundling in the time domain or CC domain (orfrequency domain). For example, when ACK/NACK full multiplexing isapplied, bundled CCs may have the same meaning as the number of CCsconfigured for the UE.

If PUCCH format 3 is used in a TDD or FDD system, the case in whichACK/NACK responses to multiple DL CCs are transmitted through one ULPUCCH may occur as described previously. Here, the meaning of ‘ACK/NACKresponses to multiple DL CCs are transmitted’ may indicate that DLtransmission exists in a PCell and one or more SCells. At this time, ifan ARI value in a PDCCH of the PCell is different from an ARI value in aPDCCH of the SCell, it is unclear which ARI value is used tocalculate/select a PUCCH resource.

Accordingly, to prevent the above problem, a value of a field (DAIfield) used for an ARI purpose on the PCell and a value of a field (TPCfield) used for an ARI purpose on the SCell should be identicallymaintained.

Embodiment 3-3

Embodiment 3-3 relates to an example of applying the same ARI value inbundled CCs and subframes.

When both Embodiments 3-1 and 3-2 are considered (e.g. when multiple CCsand multiple subframes are one bundling unit), if ARI values inrespective cells or respective subframes are different,calculation/selection of PUCCH resources may be unclear. Therefore, ARIvalues in PDCCHs in multiple subframes should also be identicallymaintained in addition to maintenance of equality of the ARI values inthe PDCCHs on the PCell and the SCell.

Embodiment 4

Embodiment 4 relates to a method of using a TPC field for PUCCH resourceallocation in a PCell-only-receiving case (i.e. the case of receivingonly a PDSCH(s) for a PCell or the case of receiving a PDCCH(s) only onthe PCell). Embodiment 4 may be applied to both cases in which ACK/NACKfull multiplexing is applied or is not applied. Embodiment 4 may also beapplied to both cases in which spatial bundling (ACK/NACK bundling formultiple codewords) is applied or is not applied.

In the above Embodiments 3, the method for determining a resource indexof a PUCCH resource (e.g. a resource of PUCCH format 3) even inPCell-only-receiving without additional physical layer signaling hasbeen described. Embodiment 3 relates to an example of using the DAI forARI purpose when the DAI is not used as original usage (usage of indexessequentially assigned for DL allocation (or PDSCH scheduling)).Accordingly, when PUCCH format 3 is used in the TDD system, if timedomain bundling or CC domain (or frequency domain) bundling issupported, DAI information needs to be used for an original purpose inorder to generate correct ACK/NACK information.

Accordingly, in Embodiment 4, the DAI is not used for other purposes ina PCell-only-receiving case. The present embodiment 4 proposes a methodof reusing a TPC field in a PDCCH(s) on the PCell as an ARI in thePCell-only-receiving case.

In a non-PCell-only-receiving case (i.e. there is PDCCH transmission inan SCell), the TPC field on the SCell is reused for the ARI as mentionedabove. However, in the PCell-only-receiving case, since there is notransmission of the TPC field on the SCell, it is necessary to define anew method for transmitting correct ACK/NACK.

According to Embodiment 4, in the PCell-only-receiving case, a TPC fieldin a specific PDCCH(s) determined according to a predetermined rule onthe PCell may be used for an original transmit power control purpose anda TPC field of the another PDCCH(s) may be used for an ARI purpose. TheUE may use only a TPC field of a specific PDCCH(s) determined accordingto a predetermined rule on the PCell for an original power controlpurpose and, upon receiving the other PDCCH(s) on the PCell, the UE mayinterpret a TPC field of the corresponding PDCCH(s) as an ARI.

If the TPC field is not used for an original purpose, the UE may miss aPDCCH including the TPC field used for power control or if the BS doesnot schedule the PDCCH, dynamic control performance for UL transmissionpower determination of the UE may be slightly reduced. However, the TPCvalue in the PDCCH is not an absolute value and a relative offset valuefor previous transmission power. Further, even if the UE does not updatethe TPC value once or twice, preset transmission power may bemaintained. In addition to the transmission power control method usingthe TPC field in the PDCCH, supplemental power control methods areprovided (this departs from the scope of the present invention and,therefore, will not be described in detail). Accordingly, missing of theTPC value does not have a substantial influence on network performance.

In applying the present invention, the TPC fields of one or more PDCCHson the PCell according to a predetermined rule may be used for anoriginal purpose (power control purpose). Hereinafter, examples of thepredetermined rule will be described.

As a first example, a TPC field of a PDCCH transmitted in an n-thsubframe of bundling subframes may be defined as being used for anoriginal purpose. Here, n may be a value indicating a partialsubframe(s) among the bundling subframes. For example, if one of thebundling subframes is indicated, n may be determined as a valueindicating a 0-th subframe or a last subframe. Moreover, n may bedifferently determined according to the number of bundling subframes (orthe size of the bundling subframes). The number of bundling subframesmay be, for example, 1, 2, 3, 4, or 9, in a similar manner as indictedin Table 12. Alternatively, a different number of subframes may bebundled according to a newly defined bundling scheme. Furthermore, n mayindicate a set of multiple subframes among bundling subframes. Forexample, when n is 0 and 1, the TPC fields of PDCCHs transmitted in the0-th and 1-th subframes among the bundling subframes may be used for anoriginal purpose. Thus, if n has a plurality of values, the number ofPDCCHs received for a fallback test, which will be described later, isincreased by the number of n values. For example, if n has two values,the number of PDCCHs received for the fallback test should be 2. In thefollowing exemplary description of the present invention, n has onevalue for convenience of description.

As a second example, the TPC field in a PDCCH having an n-th DAI valuein bundling subframes may be defined as being used for an originalpurpose. Here, n may be one of 0, 1, 2, 3, . . . . Alternatively, if theDAI value is interpreted as 1, 2, 3, 4, . . . , n may be determined asone value of 1, 2, 3, 4, . . . . In this case, even in ACK/NACK fullmultiplexing mode (the case in which time domain or CC domain (orfrequency domain) bundling is not applied), the DAI field may beincluded in a PDCCH(s) on the PCell. Further, n may be determined in theform of a set of multiple values. For example, when n is 0 and 1, thismay indicate that the TPC fields in PDCCHs having zeroth and first DAIvalues are used for an original purpose. Alternatively, when the DAIvalue is interpreted as starting from 1, if n is 1 and 2, the TPC fieldsin PDCCHs having the first and second DAI values may be indicated asbeing used for an original purpose. Thus, when n has a plurality ofvalues, the number of PDCCHs received for a fallback test, which will bedescribed later, is increased by the number of n values. For example, ifn has two values, the number of PDCCHs received for the fallback testshould be 2. In the following description of the present invention, nhas one value as an example for convenience of description.

In the above second example, the DAI value may mean successive(sequential) counters for a PDCCH(s) allocated with a size of two bitsto the UE. An actually transmitted value of the DAI field may be one of0, 1, 2, and 3 (or 00, 01, 10, and 11 when expressed as a 2-bit value)which may be interpreted by the UE as DAI values 1, 2, 3, and 4. Thiswill be described as follows in terms of a DAI value actuallytransmitted and a DAI value interpreted by the UE.

An actually transmitted value of the DAI field may be 0, 1, 2, or 3 andthe UE may interpret the value as a 1st, 2nd, 3rd, or 4th PDCCH. In thiscase, in terms of the actually transmitted DAI value, n=0 (among a setof 0, 1, 2, and 3) in a specific UE indicates the first PDCCH.

An actually transmitted value of the DAI field may be 0, 1, 2, or 3 andthe UE may interpret the value as a 1st, 2nd, 3rd, or 4th PDCCH. In thiscase, in terms of the DAI value interpreted by the UE, n=1 (among a setof 1, 2, 3, and 4) in a specific UE indicates the first PDCCH.

In summary, the actual DAI field values 00, 01, 10, and 11 included inthe PDCCHs may be mapped to the DAI values 1, 2, 3, 4 interpreted by theUE, respectively.

As described in the above examples, a TPC field in a PDCCH(s) of an n-thsubframe or a PDCCH(s) of DAI=n, determined by the value of n, is usedfor an original purpose (power control) and a TPC field in the otherPDCCH(s) may be reused as an ARI.

FIG. 31 is a flowchart illustrating an example of using a TPC field asan ARI for PUCCH resource determination in a PCell-only-receiving case.In an example of FIG. 31, it is assumed that a TPC field of one specificPDCCH determined according to predefined rule is used for an originalpurpose and a TPC field of the other PDCCH(s) is reused as an ARI.

In step S3110, a UE may receive a PUCCH resource candidate setn_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, n_(PUCCH,3) ³ includingfour resources for PUCCH format 3 through higher-layer configuration(e.g. RRC signaling).

In step S3120, when PUCCH format 3 is used for ACK/NACK transmission,the UE may determine whether a situation is a PCell-only-receiving case.If a determination result in step S3120 is NO (i.e. anon-PCell-only-receiving case), step S3130 is performed and if YES (i.e.a PCell-only-receiving case), step S3140 is performed.

In step S3130, the UE may calculate/select one PUCCH resource (i.e. oneresource index) to be used thereby from the four PUCCH resourcecandidates using an ARI indicated by reuse of a TPC field in a PDCCH(s)of an SCell.

Meanwhile, in step S3140, the UE may determine whether the number ofreceived PDCCHs is 1. Since step S3140 is performed when PDCCHs are notreceived on the SCell, the number of received PDCCHs indicates thenumber of PDCCHs received on the PCell. If a determination result instep S3140 is YES (i.e. the number of PDCCHs received on the PCell is1), step S3150 is performed and, if the determination result in stepS3140 is NO (i.e. the number of PDCCHs received on the PCell is greaterthan 1), step S3160 is performed.

In step S3150, if the UE receives only one PDCCH on the PCell, the UEmay use a TPC field of the PDCCH for an original purpose (power control)and, since there are no other PDCCHs, the UE may determine that an ARIvalue is not received. In this case, it is defined that the UE operatesin legacy LTE release-8 mode. This may be referred to as operation infallback mode. The fallback mode is the same as an ACK/NACK transmissionoperation using a conventionally defined PUCCH format 1a/1b and,therefore, a detailed description thereof will be omitted. Determinationas to whether the number of received PDCCHs is 1 in step S3140 may bereferred to as a fallback test in that whether to apply fallback mode isdetermined.

Meanwhile, since step S3160 is performed when the number of PDCCHsreceived on the PCell is greater than 1, the UE may use a TPC field inone of the PDCCHs for an original use purpose and may interpret a TPCfield of the other PDCCH(s) as being used for an ARI. Then the UE maycalculate/select one PUCCH resource (i.e. one resource index) to be usedthereby from among the four PUCCH resource candidates using the ARIindicated by reuse of the TPC field in the PDCCH of the PCell.

After step S3130 or step S3160, the UE may transmit ACK/NACK informationthrough PUCCH format 3 using a resource corresponding to thecalculated/selected index.

In the illustrated example of FIG. 31, a description has been givenunder the assumption that the UE checks only the number of received (ordetected) PDCCHs and the TPC field of the corresponding PDCCH is usedfor an original purpose when the number of received PDCCHs is 1.

However, if the number of received PDCCHs is 1, a TPC field of the PDCCHmay be used for an original purpose or may be reused for an ARI purpose.Accordingly, when the number of received PDCCHs is 1, the fallback modeoperation is not always performed and it is preferable that detaileddetermination be performed.

FIG. 32 is a flowchart illustrating another example of using a TPC fieldas an ARI for PUCCH resource determination in a PCell-only-receivingcase. In an example of FIG. 31, it is assumed that a TPC field of onespecific PDCCH determined according to a predefined rule is used for anoriginal purpose and a TPC field of the other PDCCH(s) is reused as anARI.

In the illustrated example of FIG. 32, description of the sameoperations (steps S3210, S3220, S3230, and S3240) as those of FIG. 31are omitted.

Step S3250 is performed when a determination result of step S3240 is YES(i.e. when the number of PDCCHs received on the PCell is 1). In StepS3250, it is determined whether the one received PDCCH is a predefinedPDCCH (i.e. whether the TPC field of the PDCCH is used for an originalpurpose). For example, it may be determined whether the received PDCCHis a PDCCH in the first subframe of bundling subframes. As anotherexample, it may be determined whether the received PDCCH is a PDCCH withhaving a DAI value of 1 (hereinafter, DAI=1). If a determination resultis YES, step S3260 is performed and, if NO, step S3270 is performed.

In step S3260, since the TPC field in one received PDCCH should be usedfor an original purpose, the UE may consider the ARI unknown and mayoperate in fallback mode (ACK/NACK transmission using PUCCH format1a/1b).

Step S3270 may be performed when the result of step S3240 is NO. Namely,if the number of received PDCCHs is greater than 1, since it is assumedthat there is only one PDCCH in which a TPC field is used for anoriginal purpose, the UE may recognize that a TPC field of at least onePDCCH is reused as the ARI. The UE may calculate/select one PUCCHresource (i.e. one resource index) to be used thereby among the fourPUCCH resource candidates using the ARI value from the TPC field of thecorresponding PDCCH.

Step S3270 may also be performed when a determination result of stepS3250 is NO. That is, if the number of received PDCCHs is 1, since thecorresponding PDCCH is not a PDCCH in which the TPC field is used for anoriginal purpose, the UE may recognize that the TPC field of thecorresponding one PDCCH is reused for the ARI. The UE maycalculate/select one PUCCH resource (i.e. one resource index) to be usedthereby among the four PUCCH resource candidates using the ARI valuefrom the TPC field of the corresponding PDCCH.

After step S3270, the UE may transmit ACK/NACK information through PUCCHformat 3 using a resource corresponding to the calculated/selectedindex.

Embodiment 4-1

Embodiment 4 relates to an example of applying the same ARI value inbundling subframes in a PCell-only-receiving case (i.e. the case ofreceiving only a PDSCH(s) for a PCell or the case of receiving aPDCCH(s) only on the PCell).

The term bundling subframes (or bundling window) used in description ofthe present invention means one unit consisting of DL subframes whenACK/NACK responses to DL transmissions in the DL subframes in a bundlingwindow are transmitted through one UL PUCCH, rather than a unit ofactually performing bundling in the time domain or CC domain (orfrequency domain).

For example, in an LTE release-8 TDD system, a definition as to whichprevious DL subframe(s) (subframe n-k) are used to transmit ACK/NACKresponses to DL transmissions in a specific UL subframe (subframe n) isgiven as shown in the above Table 12 (showing a DL related set index K:k₀, k₁, . . . k_(M-1)). In describing bundling subframes by way ofexample of Table 12, when ACK/NACK responses to DL transmissions in aspecific DL subframe(s) is transmitted in a specific UL subframe, thespecific DL subframe(s) is referred to as bundling subframes. Forexample, in the UL-DL configuration 4, bundling subframes for ULsubframe 2 are DL subframes 12, 8, 7, and 11 and bundling subframes forUL subframe 3 are DL subframes 6, 5, 4, and 7.

If PUCCH format 3 is used in TDD, ACK/NACK responses to DL transmissionsin multiple DL subframes may be transmitted through one UL PUCCH asdescribed previously. Here, a plurality of PDCCHs is detected inmultiple DL subframes in a PCell-only-receiving case according to theabove-described Embodiment 4. If ARI (or TPC) values indicated by thePDCCHs having TPC fields reused as ARIs are different, it is ambiguouswhich ARI value is used to calculate/select a PUCCH resource.

Here, PDCCHs having TPC fields reused as ARIs may correspond to PDCCHs(e.g. PDCCHs with a DAI value greater than 1 (hereinafter, referred toas DAI>1) except for a PDCCH having a TPC field determined to be usedfor an original purpose according to a predefined rule (e.g. a PDCCHwith DAI=1).

Accordingly, to prevent this problem, the ARI values (i.e. values of theTPC fields) of PDCCHs having TPC fields reused as ARIs (i.e. PDCCHsexcept for a PDCCH having a TPC field used for an original purpose),transmitted on the PCell in bundling subframes, should be identicallymaintained.

Embodiment 4-2

Embodiment 4-2 relates to an example of applying the same ARI value onbundled CCs.

The term bundled CCs (or bundling window) used in description of thepresent invention means one unit consisting of DL CCs when ACK/NACKresponses to the DL CCs in a bundling window are transmitted through oneUL PUCCH irrespective of presence/absence of bundling, rather than aunit of actually performing bundling in the time domain or CC domain (orfrequency domain). For example, when ACK/NACK full multiplexing isapplied, bundled CCs may have the same meaning as the number of CCsconfigured for the UE.

If PUCCH format 3 is used in a TDD or FDD system, ACK/NACK responses tomultiple DL CCs may be transmitted through one UL PUCCH as describedpreviously. Here, the meaning that ACK/NACK responses to multiple DL CCsare transmitted may correspond to the case in which DL transmissionsexist on a PCell and one or more SCells. At this time, if an ARI valuein a PDCCH having a TPC field used as an ARI on the PCell is differentfrom an ARI value in a PDCCH on the SCell, it is ambiguous which ARIvalue is used to calculate/select a PUCCH resource.

Accordingly, to prevent such a problem, the value of the field (TPCfield) used as the ARI on the PCell and the value of the field (TPCfield) used as the ARI on the SCell should be identically maintained.

Here, ARI values for PDCCHs (e.g. PDCCHs with DAI>1), except for a PDCCHdetermined to use a TPC field for an original purpose according to apredefined rule (e.g. a PDCCH with DAI=1), on the PCell and ARI valueson the SCell may be identically maintained.

Embodiment 4-3

Embodiment 4-3 relates to an example of applying the same ARI value inbundled CCs and subframes.

Namely, when the above-described Embodiments 4-1 and 4-1 aresimultaneously considered (e.g. when a plurality of CCs and a pluralityof subframes becomes one bundling unit), if ARI values in the respectivecells or respective subframes are different, it may be ambiguous tocalculate/select a PUCCH resource. Accordingly, ARIs in PUCCHs on thePCell and SCell should be identically maintained and simultaneously ARIsin PDCCHs in the plurality of subframes should be identicallymaintained.

Here, on the PCell, ARI values for PDCCHs (e.g. PDCCHs with DAI>1),except for a PDCCH determined to use a TPC field for an original purposeaccording to a predefined rule (e.g. a PDCCH with DAI=1), may beidentically maintained.

FIG. 33 is a diagram illustrating an embodiment of using a TPC field foran original purpose or an ARI purpose according to a DAI value on aPCell.

A DAI field value is used as an accumulation counter of PDCCHs per cell.That is, a DAI value is sequentially increased by one in every PUCCH ofone cell. The PDCCH is not always present in all subframes.

In the illustrated example of FIG. 33, on a PCell, PDCCHs for DLallocation are present in first and third subframes. The DAI value is 0in the PDCCH of the first subframe and is 1 in the PDCCH of the thirdsubframe. On SCells, DAI values are sequentially given in PDCCHs for DLallocation. In FIG. 33, DAI values of 0, 1, 2, 3, 0, 1, 2, 3, . . . areillustrated but these values have the same meaning as DAI values of 1,2, 3, 4, 1, 2, 3, 4, . . . from the viewpoint of the UE.

In relation to the above-described Embodiment 4, TPC fields in thePDCCHs may be used for an original purpose or an ARI purpose accordingto a DAI value on the PCell. For example, a TPC field in a PDCCH inwhich the DAI value on the PCell is 0 (or 1 from the viewpoint of theUE), i.e. a TPC field in a PDCCH in the first subframe of the PCell inFIG. 33, is used for an original purpose (i.e. power control) and a TPCfield in the other PDCCH on the PCell is reused for an ARI purpose.

In relation to the above-described Embodiments 4-1 to 4-3, ARI values inbundled subframes and/or bundled cells may be identically maintained.For example, if a bundling window is applied over four subframes andfive cells in the illustrated example of FIG. 33, the UE may assume thatvalues of TPC fields of PDCCHs on the PCell and SCells (i.e. TPC fieldsused for an ARI purpose) are the same, except for the TPC field in thefirst subframe (where DAI is 0) of the PCell.

Embodiment 5

Embodiment 5 relates to a method of using a TPC field for PUCCH resourceallocation in a PCell-only-receiving case (i.e. the case of receivingonly a PDSCH(s) for a PCell or the case of receiving a PDCCH(s) only onthe PCell). Embodiment 5 is applied to partial ACK/NACK bundling.Partial bundling refers to bundling only in a time domain or in a CCdomain (or frequency domain).

A DAI field is basically used for an original purpose (i.e. for anaccumulation counter of PDCCHs on each cell) as in the above Embodiment4 and a TPC field in a PDCCH may be reused as an ARI. In this case, aTPC field of a predetermined specific PDCCH is used for an originalpurpose. The specific PDCCH may be determined as a PDCCH of an n-thsubframe in bundling subframes (this part has been described in theabove Embodiment 4 and, therefore, a repeated description is omitted).Alternatively, a PDCCH in which a TPC field is used for an originalpurpose may be determined based on a DAI value.

The above examples of FIG. 31 or 32 may be substantially identicallyapplied to Embodiment 5 as a basic operation and a repeated descriptionwhich has been given in the above Embodiment 4 is omitted.

Hereinafter, a detailed method of using the TPC field for an originalpurpose or an ARI purpose based on a DAI value when partial ACK/NACKbundling is applied will be described.

First, a TPC field in a PDCCH having an n-th DAI value in bundlingsubframes of a PCell may be defined as being used for an originalpurpose. Values of the DAI fields may be given as 0, 1, 2, 3, . . . ormay be given as 1, 2, 3, 4, . . . from the viewpoint of the UE.

In this case, in an ACK/NACK partial bundling mode (applied to timedomain bundling or CC domain (or frequency domain) bundling), DAI fieldsmay be included in a PDCCH(s) on the PCell. Here, values of the DAIfields included in the PDCCH(s) of the PCell should be determined basedon a predetermined rule and a detailed proposal of the present inventiontherefor will be described hereinbelow.

When ACK/NACK partial bundling is applied, if a TPC field in a PDCCH ofDAI=n is used for an original purpose (power control), a DAI field of aPDCCH(s) may be determined in a various manner as follows.

In legacy (LTE release-8) TDD mode, a DAI indicates an accumulated valueof PDCCHs allocated to a UE and, if the DAI is simply applied to amulticarrier environment, the DAI may be used as an accumulated value ofPDCCHs allocated to the UE over all cells (or CCs). For example, asshown in FIG. 34, when ACK/NACK bundling is applied in four subframesand on two CCs, the DAI value may be determined such that the DAI valueis increased in the direction that a CC index in a bundling window isincreased. However, it is difficult to apply this scheme to partialbundling. Accordingly, in LTE release-10 TDD mode in which a pluralityof CCs (or cells) is configured, another method for determining the DAIvalue needs to be provided.

FIG. 35 is a diagram illustrating examples for determining DAI values ina CA TDD system.

As an example, a DAI value may indicate the accumulated number of PDCCHsallocated to the UE in a plurality of subframes per cell (FIG. 35( a)).For example, such a method for determining the DAI value is preferablyused when bundling is applied in the time domain. The accumulated numberof PDCCHs may be applied in a manner of counting PDCCHs in all subframesin one radio frame. Alternatively, the accumulated number of PDCCHs maybe applied in a manner of counting PDCCHs in a real bundling window (aunit for actually performing ACK/NACK bundling) in the time domain. Inthe example of FIG. 35( a), DAIs in PDCCHs in three subframes in a realbundling window of a unit of four subframes on SCell #2 are determinedas 0, 1, and 2 and this is an example of using DAI fields asaccumulation counters indicating that corresponding PUCCHs are a firstPDCCH, a second PDCCH, and a third PDCCH, respectively.

As another example, a DAI value may indicate the total number of PDCCHsallocated to the UE on a plurality of CCs (or cells) per subframe (FIG.35( b)). For example, such a DAI value determination method ispreferably used when partial bundling is applied in the CC domain. Thetotal number of PDCCHs may be determined as the number of PDCCHs in allCCs configured for the UE. Alternatively, the total number of PDCCHs maybe determined as the number of PDCCHs in a real bundling window (a unitfor really performing ACK/NACK bundling) in the CC domain. In theexample of FIG. 35( b), the DAI value in PDCCHs in the first subframe is2 and this is an example of using a DAI field as an indicator indicatingthe total number of PDCCHs in the corresponding subframe is 3.

Alternatively, the DAI value may be determined as the accumulatedcounter of PDCCHs allocated to the UE in a plurality of CCs (or cells)per subframe. The accumulated number of PDCCHs may be counted for everyPDCCHs according to an increased order of a CC index (or a cell index)in all CCs configured for the UE or according to an increased order ofCC indexes (or cell indexes) in a real bundling window in the CC domain.For instance, in the example of FIG. 35( b), DAI values in the thirdsubframe are determined as DAI=0 on a PCell, DAI=1 on SCell #2, DAI=2 onSCell #3, and DAI=3 on SCell #4.

As illustrated in FIG. 35( a), if the DAI is used as the accumulationcounter of PDCCHs allocated in a real bundling window in the time domain(i.e. if the DAI value is reset on each CC), the embodiment of thepresent invention using the TPC fields of PDCCHs on a PCell and SCells,except for a PDCCH having a specific DAI value (e.g. DAI=0) on thePCell, for an ARI purpose may be identically applied.

Meanwhile, as illustrated in FIG. 35( b), if the DAI is used as thetotal number (or accumulation counter) of PDCCHs allocated in a realbundling window in the CC domain (or frequency domain), the embodimentof the present invention using the TPC fields of PDCCHs on a PCell andSCells, except for a PDCCH having a specific DAI value (e.g. DAI=0) onthe PCell, for an ARI purpose may be difficult to apply.

For example, it may be assumed that PDCCHs are allocated to a specificUE in the first subframe and the second subframe and PDCCHs are notallocated on SCells. Although this case corresponds toPCell-only-receiving, DAI values of the PDCCHs received by the UE arethe same in the two subframes (e.g. DAI=0) (if the DAI field is used asan indicator or accumulation counter of the total number of PDCCHs in acorresponding subframe, a DAI value is 0 according to the aboveassumption). Then, it is ambiguous for the UE to determine which TPCfield of a PDCCH of the two PDCCHs on the PCell is used for an ARIpurpose and which TPC field of a PDCCH is used for an original purpose.In other words, if the DAI value is determined by the reset scheme ofthe DAI value per subframe, the embodiment of the present invention ofusing the TPC fields of PDCCHs on a PCell and SCells, except for a PDCCHhaving a specific DAI value (e.g. DAI=0) on the PCell, for an ARIpurpose cannot be applied.

To solve the above problem, different DAI value determination methodsmay be applied on the PCell and SCell. For example, on the SCell, theDAI may be used as an accumulation counter of PDCCHs allocated in a realbundling window in the frequency domain (or CC domain) and, on thePCell, the DAI may be used as an indicator (or accumulation counter) ofthe total number of PDCCHs allocated in a real bundling window in thetime domain.

Alternatively, to apply the present embodiment, it is necessary todefine the DAI at least on the PCell as an accumulation counter ofPDCCHs in the time domain. Accordingly, the DAI of the PDCCH(s) on thePCell may be used as the accumulation counter of the PDCCH allocated ina real bundling window in the time domain and the DAI of a PDCCH(s) onthe SCell may be used in the same or different manner as or from the DAIused on the PCell.

In the examples of the present invention which will be describedhereinbelow, it is assumed that a DAI field of a PDCCH is used asfollows.

First, a DAI field in a PDCCH may be used as an accumulation counter ofPDCCHs allocated in a plurality of subframes in a bundling window perCC. That is, DAI values are independently determined on each CC. Here,bit values 0, 1, 2, and 3 of the DAI field indicate accumulation counts1, 2, 3, and 4, respectively. That is, bit values expressed as 0, 1, 2,and 3 from the viewpoint of the DAI field may also be expressed as 1, 2,3, and 4 from the viewpoint of a DAI value interpreted by the UE.

Next, the DAI field of the PDCCH may also be used an indicator of thetotal number of PDCCHs allocated on a plurality of CCs in a bundlingwindow in each subframe. The bit values 0, 1, 2, and 3 of the DAI fieldmay mean the total numbers 1, 2, 3, and 4, respectively. That is, bitvalues expressed as 0, 1, 2, and 3 from the viewpoint of the DAI fieldmay also be expressed as 1, 2, 3, and 4 from the viewpoint of the UE.

FIGS. 36 to 39 illustrate various examples of using DAI fields in CCdomain bundling. In the examples of FIGS. 36 to 39, five CCs configuredfor a UE and a 4DL-1UL configuration in TDD (i.e. ACK/NACK responses toDL transmissions in four DL subframes are gathered to transmit theresponses through a PUCCH of one UL subframe) are illustrated. Inaddition, in the illustrated examples of FIGS. 36 to 39, a bundlingwindow includes five CCs and four subframes. However, the cases in whichthe maximum size of a real bundling window is 4, 5, or 2 are illustratedin FIGS. 36 to 39.

FIG. 36 illustrates an example in which CC domain bundling is notapplied on a PCell (the maximum size of a real bundling window in the CCdomain is 4). In this case, a DAI field of the PCell is used as anaccumulation counter of PDCCHs allocated to subframes on the PCell. ADAI field of an SCell may be used as indicators of the total number ofPDCCHs allocated to SCells except for the PCell in each subframe.

FIG. 37 illustrates an example in which CC domain bundling is notapplied on a PCell (the maximum size of a CC-domain real bundling windowis 4). In this case, a DAI field of the PCell is used as an accumulationcounter of PDCCHs allocated to subframes on the PCell. A DAI field of anSCell may be used as an indicator of the total number of PDCCHsallocated to the PCell and SCells in each subframe. Accordingly, the UEcan be aware of the total number of PDCCHs allocated by the BS (i.e. thetotal number of PDCCHs on both the PCell and the SCell) in acorresponding subframe from the DAI of the SCell. The UE may determinewhether there is a PDCCH that the UE fails to detect/receive in a realbundling window, using the DAI of the PCell together with informationabout the total number of the allocated PDCCHs. Therefore, CC-domainACK/NACK bundling in a corresponding subframe can be effectivelyperformed.

For example, in the illustrated example of FIG. 37, if a DAI value inPDCCHs detected by the UE on SCells in the second subframe is 2, the UEcan recognize that the total number of PDCCHs allocated on the PCell andSCells is 3. Here, it may be assumed that the UE does not receive aPDCCH in SCell#2. In this case, it cannot determined only by the DAIvalue on the SCells whether the PDCCH which is not received is a PDCCHin a real bundling window (i.e. on the SCell) or a PDCCH in a window(i.e. on the PCell) except for the real bundling window. Because a DAIvalue on the PCell is given as an accumulation count in the time domain,the UE may confirm that DAI values are sequentially provided in thefirst and third subframes on the PCell and thus confirm that there is noPDCCH that the UE fails to detect on the PCell. Consequently, the UE canbe aware of the fact that PDCCH detection fails in one of the SCells inthe second subframe.

FIG. 38 illustrates an example in which CC domain bundling is appliedirrespective of a PCell or SCells (the maximum size of a CC-domain realbundling window is 5). In this case, a DAI field of the PCell is used asan accumulation counter of PDCCHs allocated to subframes on the PCell. ADAI field of an SCell may be used to indicate the total number of PDCCHsallocated on both the PCell and the SCell in each subframe. Accordingly,the UE can be aware of the total number of PDCCHs allocated by the BS(the total number of PDCCHs in both the PCell and the SCell) in asubframe by the DAI of the SCell. Since the DAI value indicates thenumber of PDCCHs in a real bundling window, the UE may determine whetherthere is a PDCCH that the UE fails to detect/receive in the realbundling window. Hence, CC-domain ACK/NACK bundling in a correspondingsubframe can be effectively performed.

FIG. 39 illustrates the case in which the maximum size of a CC-domainreal bundling window is 2. At this time, CC-domain bundling is notapplied on a PCell and two real bundling windows having the maximum sizeof 2 may be configured on four SCells. A DAI field of the PCell is usedas an accumulation counter of PDCCHs allocated to subframes on thePCell. A DAI field of the SCell may be used as an indicator of the totalnumber of PDCCHs allocated on the SCells (a maximum of two SCells) in areal bundling window except for the PCell in each subframe.

ACK/NACK partial bundling (bundling in the time domain or frequencydomain) is applied to Embodiment 5 and, even in this case, the ACK/NACKbundling operation may be unclear when ARI (=TPC field) values in abundling window are different.

Accordingly, in a PCell-only-receiving case, ARI values of PDCCHs inwhich TPC fields on a PCell in bundled subframes are reused for an ARIpurpose (i.e. except for a PDCCH in which a TPC is used for an originalpurpose) can be identically maintained. In addition, on bundled CCs,values of fields (=TPC fields) used for an ARI purpose on a PCell can beidentically maintained with values of fields (=TPC fields) used for anARI purpose) on an SCell. Further, on bundled CCs and subframes, ARIvalues for PDCCHs (e.g. PDCCHs with DAI>1), except for a PDCCHdetermined to use a TPC field for an original use according to apredefined rule (e.g. PDCCH with DAI=1), on a PCell can be identicallymaintained. In association therewith, the principle of the presentinvention described in the above Embodiments 4-1 to 4-3 may be appliedin the same manner to the present Embodiment 5. For clarity, descriptionof repetitive parts is omitted.

UL ACK/NACK Transmission for DL SRS Transmission in Multicarrier SupportSystem

The LTE release-8 system supports SPS. If DL SPS transmission isactivated, time/frequency resource for SPS transmission may bepre-allocated by a PDCCH and a PDSCH without a corresponding PDCCH maybe transmitted through the allocated resource.

ACK/NACK feedback related to SPS may be divided into two types. One typeis that ACK/NACK feedback for ‘PDCCH indicating DL SPS release detectedby a UE within a subframe(s) n-k’ is transmitted in subframe n. Theother type is that ACK/NACK feedback for ‘PDSCH transmissions without acorresponding PDCCH within a subframe(s) n-k’ is transmitted in subframen. The first type corresponds to the case in which if a PDCCH is presentin an (n-k)-th subframe(s) (where k may be one or multiple values),ACK/NACK feedback for the PDCCH is transmitted in an n-th subframe. Thesecond type corresponds to the case in which if SRS transmission isreceived in an (n-k)-th subframe(s) without an additional PDCCH afterSPS activation, ACK/NACK feedback for corresponding SPS transmission isregularly transmitted in an n-th subframe. For a detailed descriptionrelated to SPS transmission, reference may be made to a document of 3GPPTS 36.213.

A PUCCH resource index for ACK/NACK feedback in the LTE release-8 systemis basically determined based on a CCE index of a PDCCH. If an ACK/NACKresponse in one PUCCH in an n-th subframe includes an ACK/NACK responsefor one or more PDCCHs (including a general PDCCH and a PDCCH indicatingDL SPS release) in an (n-k)-th subframe(s), a PUCCH resource index maybe derived from a CCE index of the PDCCH. However, if only an ACK/NACKresponse to SPS without a PDCCH in an (n-k)-th subframe(s) should betransmitted, a PUCCH resource index for the ACK/NACK response cannot bedetermined. To solve such a problem, in the LTE release-8 system, aPUCCH resource index set (e.g. one set consisting of four PUCCH resourceindexes) for the case in which only ‘PDSCH transmission without acorresponding PDCCH’ (i.e. SPS PDSCH transmission) is present ispre-indicated through RRC signaling. Moreover, it is determined througha TPC field in a PDCCH indicating SPS activation whether one PUCCHresource of the PUCCH resource index set is used. A mapping relationshipbetween a PUCCH resource index n_(PUCCH) ⁽¹⁾ for DL SPS and a value of aTPC field is defined in Table 14 shown below.

TABLE 14 Value of ‘TPC command for PUCCH’ n_(PUCCH) ⁽¹⁾ ‘00’ The firstPUCCH resource index configured by the higher layers ‘01’ The secondPUCCH resource index configured by the higher layers ‘10’ The thirdPUCCH resource index configured by the higher layers ‘11’ The fourthPUCCH resource index configured by the higher layers

If the above-mentioned DL SPS transmission is performed in amulticarrier support system, it is necessary to provide an ACK/NACKtransmission method considering DL SPS transmission.

Various embodiments of the present invention therefor are described onthe premise that, similarly to the above-described Embodiments 4 and 5,a TPC field of a first PDCCH (a PDCCH with DAI=1 (DAI=1, 2, 3, 4, . . .)) of a PCell for a specific UE is used for a power control purpose ofan original purpose and a TPC field of the other PDCCH(s) is used for anARI purpose. Notably, such an assumption is for clarity of descriptionand application examples of the present invention are not limitedthereto. Namely, ARI information may be provided by other methods.

When an ACK/NACK response to ‘PDSCH transmission without a correspondingPDCCH’ (hereinafter, referred to as ‘SPS without a PDCCH’) in an(n-k)-th subframe(s) is transmitted in an n-th subframe, SPS without aPDCCH may be received in the (n-k)-th subframe(s) and, in additionthereto, one PDCCH may be detected. Then, an ACK/NACK response to thePDCCH and an ACK/NACK response to the SPS without PDCCHs need to betransmitted. Here, if one detected PDCCH is a first PDCCH (e.g. a PDCCHwith DAI=1), since a TPC field of the PDCCH is used for an originalpurpose, this case is when the UE does not receive ARI information.Therefore, the UE cannot determine a resource index for PUCCH format 3.Hereinafter, various embodiments of the present invention for solvingthe above problem will be described.

In the following description, ACK/NACK transmission is needed in one ofthe following three cases. In summary, Case 1 is ACK/NACK for a ‘PDSCHwith a PDCCH’, Case 2 is ACK/NACK for a ‘DL SPS release PDCCH’, and Case3 is ACK/NACK to a ‘DL SPS PDSCH’.

Case 3 may be referred to as ‘PDSCH without a corresponding PDCCH’,ACK/NACK for ‘SPS without a PDCCH’, or simply ACK/NACK for ‘SPS’. InCase 1, a PDCCH of ‘PDSCH with a PDCCH’ may be referred to as a ‘PDCCHcorresponding to a PDSCH’.

Embodiment 6

Embodiment 6 relates to a method for transmitting an ACK/NACK responsealways using PUCCH format 3.

A PUCCH format 3 resource index set for SPS only may be indicated to theUE through RRC signaling. For example, information about a setconsisting of n_(PUCCH,0) ³, n_(PUCCH,1) ³, n_(PUCCH,2) ³, andn_(PUCCH,3) ³ in the form shown in the above Table 13 may be provided tothe UE. In addition, it may be designated through a TPC field in a PDCCHindicating SPS activation which resource index of the PUCCH format 3resource index set is to be used.

As an example, when ACK/NACK feedback for only SPS without a PDCCH isneeded, a specific PUCCH format 3 resource index indicated through anSPS activation PDCCH out of an RRC configured set may be selected andused. That is, ACK/NACK only for SPS without a PDCCH may be transmittedusing PUCCH format 3.

As another example, the following methods may be applied to the case inwhich ACK/NACK feedback for ‘SPS without a PDCCH’ and ‘one PDSCH with aPDCCH’ is needed.

A first method is to select and use a PUCCH format 3 resource indexindicated through an SPS activation PDCCH, That is, ACK/NACK responsesto the ‘SPS without a PDCCH’ and ‘one PDSCH with a PDCCH’ may also betransmitted PUCCH format 3.

A second method is again divided into two methods according to whetherARI information is included in one ‘PDCCH corresponding to a PDSCH’.

When one ‘PDCCH corresponding to a PDSCH’ is a PDCCH which does notinclude ARI information (e.g. a PDCCH in which a first DAI (DAI=1)), aPUCCH format 3 resource index indicated through SPS activation PDCCH maybe selected and used. That is, even through the ARI information is notacquired from the ‘PDCCH corresponding to a PDSCH’, ACK/NACK responsesto the ‘SRS without a PDCCH’ and ‘one PDSCH with a PDCCH’ may betransmitted using PUCCH format 3.

If one ‘PDCCH corresponding to a PDSCH’ is a PDCCH including the ARIinformation (e.g. a PDCCH which does not have a first DAI (DAI>1) (thiscase may be when the UE misses a PDCCH having the first DAI), a PUCCHformat 3 resource index using an ARI value indicated by a TPC field inthe ‘PDCCH corresponding to a PDSCH’ may be selected and used.

Meanwhile, when a plurality of ACK/NACK feedbacks including ACK/NACK forthe ‘SPS without a PDCCH’ is transmitted, the PUCCH format 3 resourceindex may be determined by an ARI value indicated by a TPC field ofsecond or more PDCCHs on a PCell (e.g. PDCCH(s) in which DAI>1) or aPDCCH(s) on an SCell(s).

Embodiment 7

Embodiment 7 relates to a method for operating ACK/NACK for transmissionof ‘only’ SPS without a PDCCH always in fallback mode. Here, thefallback mode refers to ACK/NACK transmission according to an operationdefined in LTE release-8, for example, ACK/NACK transmission using PUCCHformat 1a/1b. On the other hand, for ACK/NACK transmission for ‘SPSwithout a PDCCH’ and other DL transmission (a PDSCH with a PDCCH), PUCCHformat 3 may be used.

To this end, a PUCCH format 1a/1b resource index set to be used fortransmission of ‘only’ SPS may be indicated to the UE through RRCsignaling. The PUCCH format 1a/1b resource index set may be configuredas shown in Table 14 or may be configured according to other schemes.When SPS activation is indicated, which index of the PUCCH resourceindex set is to be used may be designated through a TPC field in an SPSactivation PDCCH.

Because time/frequency resources for SPS transmission are preset betweenthe BS and the UE, the BS and the UE know when ACK/NACK feedback for the‘SPS without a PDCCH’ is transmitted and received. Accordingly, in abundling window including SPS to a specific UE, the BS may use TPCfields of all PDCCHs for an ARI purpose without separatelydistinguishing between PDCCHs on a PCell. That is, during transmissionof ACK/NACK feedback for only the SPS without a PDCCH, a PDCCH(s)transmitted in a bundling window including SPS without a PDCCH may useall TPC fields for an ARI purpose without distinguishing between a PCelland SCells.

In this case, a TPC field of a PDCCH is not used for an original purpose(UL transmit power control) with respect to a PUCCH transmittingACK/NACK feedback for the SPS without a PDCCH. However, a TPC value in aPDCCH is a relative offset value for previous transmit power rather thanan absolute value and, even if the UE does not update the TPC value onceor twice, preset transmit power is maintained. In addition to thetransmit power control method of using the TPC field in the PDCCH,supplemental power control methods are provided. Furthermore, whentransmission of SPS without a PDCCH is needed in FDD mode, it is definedthat the UE cannot obtain a TPC value of an original purpose.Accordingly, even when TPC of an original purpose is not applied,network performance is not substantially influenced by operationdescribed in the above examples of the present invention in TDD.

According to the example of Embodiment 7, when ACK/NACK feedback foronly SPS without a PDCCH is needed, a specific PUCCH format 1a/1bresource index indicated through an SPS activation PDCCH of an RRCconfigured set may be selected and used. That is, for ACK/NACK for onlythe SPS without a PDCCH, a fallback mode operation using PUCCH format1a/1b may be performed.

As another example, when ACK/NACK feedbacks for ‘SPS without a PDCCH’and ‘one PDSCH with a PDCCH’ are needed, since TPC fields of all PDCCHsin a bundling window are used for an ARI purpose as describedpreviously, a PUCCH format 3 resource index may be selected and usedaccording to an ARI value indicated by a TPC field of one detectedPDCCH.

Meanwhile, when a plurality of ACK/NACK feedbacks including ACK/NACK forSPS without a PDCCH is transmitted, since TPC fields of all PDCCHs in abundling window are used for an ARI purpose as described above, thePUCCH format 3 resource index may be determined by an ARI value(s)indicated by a TPC field of a PDCCH(s) on a PCell and/or an SCell.

Embodiment 8

Embodiment 8 relates to a method for performing ACK/NACK for DLtransmission ‘including’ SPS transmission without a PDCCH always infallback mode.

To this end, a PUCCH format 1a/1b resource index set to be used fortransmission of ‘only’ SPS without a PUCCH may be indicated to the UEthrough RRC signaling. The PUCCH format 1a/1b resource index set may beconfigured as shown in Table 14 or may be configured according to otherschemes. When SPS activation is indicated, which index of the PUCCHresource index set is to be used may be designated through a TPC fieldin an SPS activation PDCCH.

According to an example of Embodiment 8, when ACK/NACK feedback for‘only’ SPS without a PDCCH is needed, a specific PUCCH format 1a/1bresource index indicated through an SPS activation PDCCH of an RRCconfigured set may be selected and used. That is, for ACK/NACK of onlySPS without a PDCCH, fallback mode using PUCCH format 1a/1b may beperformed. Here, ACK/NACK feedback for SPS without a PDCCH may have asize of 1 or 2 bits according to the number of codewords and PUCCHformat 1a or 1b may be used.

As another example, ACK/NACK feedbacks for ‘SPS without a PDCCH’ and‘one PDSCH with a PDCCH’ are needed, a specific PUCCH format 1a/1bresource index indicated through an SPS activation PDCCH of an RRCconfigured set may be selected and used. That is, even for ACK/NACKfeedback for transmission including SPS without a PDCCH, fallback modeusing PUCCH format 1a/1b may be performed. Here, a 2-bit to O-bitfeedback payload is needed according to the number of codewords for eachof the ‘SPS without a PDCCH’ and ‘one PDSCH with a PDCCH’ (this isbecause a 1-bit ACK/NACK response bit is generated with respect to onecodeword when spatial bundling is not applied).

Hereinafter, detailed examples of the present invention will bedescribed when ACK/NACK feedbacks for SPS without a PDCCH’ and ‘onePDSCH with a PDCCH’ are needed.

Embodiment 8-1

Embodiment 8-1 relates to a method of using a channel selection schemeof M=2, 3, or 4 when ACK/NACK feedbacks for SPS without a PDCCH’ and‘one PDSCH with a PDCCH’ are needed. Namely, the size of an ACK/NACKfeedback payload for ‘SPS without a PDCCH’ and ‘one PDSCH with a PDCCH’is 2 to 4 bits and, to transmit the ACK/NACK feedbacks without any loss,a channel selection scheme using two, three, or four PUCCH formats 1b(or PUCCH formats 1a) may be applied. When use of a channel selectionscheme for PUCCH format 1b (or 1a) defined in LTE release-8 may beexpressed as operation in fallback mode using a channel selecting schemeof LTE release-8.

Among a plurality of resources used for channel selection, one PUCCHformat 1b (or 1a) resource is derived from a CCE index of a ‘PDCCHcorresponding to a PDSCH’ and another PUCCH format 1b (or 1a) resourcemay be indicated through a PDCCH indicating SPS activation. ACK/NACKinformation may be transmitted by the channel selection scheme ofselecting one of the two PUCCH format 1b (or 1a) resources.

Additionally, if a PUCCH resource is further needed (e.g. M=3 or 4), aPUCCH resource corresponding to a value (CCE index+offset) obtained byadding a prescribed offset (e.g. 1) to a CCE index of a ‘PDCCHcorresponding to a PDSCH’ may be used for channel selection. A PUCCHresource corresponding to a value obtained by adding a resource indexassigned through an SPS activation PDCCH to the prescribed offset(e.g. 1) may be used for channel selection, instead of or together withan additional resource based on the CCE index of the ‘PDCCHcorresponding to a PDSCH’.

Alternatively, similarly to the above scheme, a channel selection schemeusing PUCCH format 1a/1b resource indexes explicitly and/or implicitlydetermined from information related to the ‘SPS without a PDCCH’ and‘one PDSCH with a PDCCH’ may be applied.

When the UE determines PUCCH resources for transmitting ACK/NACKinformation according to Embodiment 8-1, the BS may attempt to receiveACK/NACK information with respect to three cases of a PUCCH format 3region, a PUCCH format 1a/1b region, and a channel selection (PUCCHformat 1b (or 1a)) region.

Since the UE may transmit ACK/NACK information using any one of thethree cases, the BS should perform blind decoding in the above threecases.

Embodiment 8-2

Embodiment 8-2 relates to a method of using fallback mode using PUCCHformat 1b (or 1a) defined in LTE release-8 using spatial bundling (i.e.ACK/NACK bundling for multiple codewords) when ACK/NACK feedbacks for‘SPS without a PDCCH’ and ‘one PDSCH with a PDCCH’ are needed.

First, when an ‘SPS without a PDCCH’ corresponds to transmission ofmultiple (e.g. two) codewords, spatial bundling is performed on anACK/NACK response thereto. Similarly, when ‘one PDSCH with a PDCCH’corresponds to transmission of multiple (e.g. two) codewords, spatialbundling is performed on an ACK/NACK response thereto. If only one ofthe ‘SPS without a PDCCH’ and ‘one PDSCH with a PDCCH’ is one-codewordtransmission and the other is two-codeword transmission, spatialbundling is performed only with respect to two-codeword transmission.

Accordingly, the size of an ACK/NACK payload for the ‘SPS without aPDCCH’ and ‘one PDSCH with a PDCCH’ is reduced to two bits when spatialbundling is performed from as compared with two or four bits whenspatial bundling is not performed.

2-bit ACK/NACK feedback may be transmitted through PUCCH format 1b (or1a) of legacy LTE release-8. That is, if spatial bundling is performed,ACK/NACK feedback may operate in fallback mode using PUCCH format 1b (or1a) of LTE release-8.

In this case, a PUCCH format 1a/1b resource index derived from a CCEindex of one ‘PDCCH corresponding to a PDSCH’ may be selected and used.Alternatively, a PUCCH format 1a/1b resource index indicated through anSPS activation PDCCH out of an RRC configured resource index set may beselected and used. In other words, respective ACK/NACK responses fallback to PUCCH format 1a and multiplexed through phase rotation, i.e. oneof two ACK/NACK responses is mapped to an I channel and the other ismapped to a Q channel. Alternatively, two ACK/NACK responses fall backto PUCCH format 1b and multiplexed.

For example, in two-bit ACK/NACK used in PUCCH format 1b used in LTErelease-8, a Most Significant Bit (MBS) may be mapped to ACK/NACK forthe ‘SPS without a PDCCH’ and a Least Significant Bit (LSB) may bemapped to ACK/NACK for the ‘one PDSCH with a PDCCH’ (e.g. a PDCCH withDAI=1). Alternatively, ACKs/NACKs may be mapped in the reverse of theabove example.

As another embodiment, ACK/NACK for the ‘SPS without a PDCCH’ is mappedto the I axis of a QPSK constellation and ACK/NACK for the ‘one PDSCHwith a PDCCH’ (e.g. a PDCCH with DAI=1) may be mapped to the Q axis of aQPSK constellation. Alternatively, ACKs/NACKs may be mapped in thereverse manner to the above example. In addition, according to areceived time order, ACK/NACK for first reception of the ‘SPS without aPDCCH’ and ‘one PDSCH with a PDCCH’ is mapped to the I axis and ACK/NACKfor later reception may be mapped to the Q axis. Alternatively,ACKs/NACKs may be mapped in the reverse manner to the above example.

For example, when ACK/NACK for the ‘SPS without a PDCCH’ is mapped tothe I axis and the ‘one PDSCH with a PDCCH’ (e.g. a PDCCH with DAI=1) ismapped to the Q axis, even if the UE fails to detect a PDCCH (i.e. a‘PDCCH corresponding to a PDSCH’), the BS may receive an ACK/NACKresponse for at least SPS. This is because, when the UE fails to detecta PDCCH, a constellation location when ACK/NACK for the ‘SPS without aPDCCH’ is mapped to the I axis is equal to a constellation location whenACK/NACK for ‘only’ the ‘SPS without a PDCCH’ is transmitted using BPSKconstellation (i.e. I axis) using PUCCH format 1a.

As another example, ‘1,1’ and ‘0,0’ of the QPSK constellation may bemapped to ACK/NACK for the ‘SPS without PDCCH’ and ‘0,1’ and ‘1,0’ maybe mapped to ACK/NACK for the ‘one PDSCH with a PDCCH’ (e.g. a PDCCHwith DAI=1). Alternatively, the respective ACKs/NACKs may be mapped inthe reverse manner to the above example.

The above constellation mapping may be identically applied to the casewhere transmission mode in each cell is MIMO mode and the other cases.The above constellation mapping may also be applied irrespective ofwhether spatial bundling is actually applied (i.e. irrespective ofwhether 2-codeword transmission is present).

In applying Embodiment 8-2, spatial bundling may be applied even toACK/NACK feedback for ‘only’ SPS without PDCCH. In this case, the BSshould perform blind decoding for three cases of a PUCCH format 1a/1bregion for ACK/NACK for ‘only’ SPS, a PUCCH format 1a/1b region forACK/NACK for the ‘SPS without a PDCCH’ and ‘the PDSCH with a PDCCH’, anda PUCCH format 3 region.

Additionally, in applying Embodiment 8-2, instead of a resource indexderived from a CCE index of the ‘PDCCH corresponding to a PDSCH’ as aPUCCH resource, a PUCCH resource index designated through an SPSactivation PDCCH of an RRC configured PUCCH resource set may be used andthe other parts may be identically applied.

Embodiment 8-3

Embodiment 8-3 relates to a method for applying spatial bundling (i.e.ACK/NACK bundling for multiple codewords) and using a channel selectionscheme of M=2, when ACK/NACK feedbacks for an ‘SPS without a PDCCH’ and‘one PDSCH with a PDCCH’ are needed. When a channel selection scheme forPUCCH format 1b (or 1a) defined in LTE release-8 is used, this may beexpressed as a fallback mode operation using the channel selectionscheme of LTE release-8.

First, in the case of transmission of multiple (e.g. two) codewords forthe ‘SPS without a PDCCH’, spatial bundling is performed on an ACK/NACKresponse thereto. Similarly, in the case of transmission of multiple(e.g. two) codewords for the ‘one PDSCH with a PDCCH’, spatial bundlingis performed on an ACK/NACK response thereto. If one of the ‘SPS withouta PDCCH’ and ‘one PDSCH with a PDCCH’ is one codeword and the other istwo codewords, spatial bundling is performed only with respect totransmission of the two codewords.

Accordingly, the size of an ACK/NACK payload for the ‘SPS without aPDCCH’ and ‘one PDSCH with a PDCCH’ is reduced to two bits when spatialbundling is performed from two or four bits when spatial bundling is notperformed.

2-bit ACK/NACK feedback may be transmitted through PUCCH format 1b (or1a) of legacy LTE release-8. Here, a channel selection scheme of M=2using PUCCH format 1b(/1a) may be used. That is, 2-bit ACK/NACK feedbackas a result of performing spatial bundling may be transmitted usingfallback mode of PUCCH format 1b(/1a).

Here, M=2 may mean transmission of two types of ACK/NACK information(2-bit ACK/NACK information) as a spatial bundling result or may meanchannel selection using two PUCCH resources. Thus, detection performanceof the BS can be improved by using channel selection.

Of two PUCCH resources for channel selection, the first PUCCH resourcemay use a PUCCH format 1a/1b resource index designated through an SPSactivation PDCCH and the second PUCCH resource may use a PUCCH format1a/1b resource index derived from a CCE index of the ‘PDCCHcorresponding to a PDSCH’. As opposed to the above example, the firstand second PUCCH resources may be mapped to a PUCCH resource indexdesignated through the SPS activation PDCCH and a PUCCH resource indexderived from a CCE index of the ‘PDCCH corresponding to a PSDCH’,respectively. ACK/NACK information can be transmitted by the channelselection scheme of selecting one of two PUCCH format 1b (or 1a)resources.

In the present embodiment, a channel selection mapping relationshipbetween ACK/NACK information and a PUCCH resource may be configured asshown in, for example, Table 5 or Table 8. However, this is purelyexemplary and a new channel selection mapping relationship may bedefined and used.

As an example of this embodiment, it is assumed that a channel mappingrelationship using PUCCH format 1b is given as shown in Table 5. Of twoPUCCH resources (n_(PUCCH,0) ⁽¹⁾ and n_(PUCCH,1) ⁽¹⁾) used for channelmapping, a PUCCH resource designated through the SPS activation PDCCHmay be mapped to n_(PUCCH,0) ⁽¹⁾ and a PUCCH resource derived from a CCEindex of the ‘PDCCH corresponding to a PDSCH’ may be mapped ton_(PUCCH,1) ⁽¹⁾. Such mapping configuration may be determined regardlessof a reception order (a received time) of the ‘SPS without a PDCCH’ andthe ‘PDCCH corresponding to a PDSCH’. For example, even when a specificUE transmits a response after missing a PDCCH (i.e. ‘PDCCH correspondingto a PDSCH’) and receiving only SPS, the UE may receive an ACK/NACKresponse to at least the SPS. This is because, when the UE fails todetect a PDCCH, a PUCCH resource (n_(PUCCH,0) ⁽¹⁾) used for ACK/NACKtransmission for the ‘SPS without a PDCCH’ is identical to a PUCCHresource (n_(PUCCH,0) ⁽¹⁾) used for ACK/NACK transmission for ‘only’ theSPS without a PDCCH. Meanwhile, as a modified example of thisembodiment, the respective PUCCH resources and DL transmission types(PDCCH or SPS) may be mapped oppositely to the above example or may bemapped according to order of received time.

As another example of this embodiment, in a channel mapping relationshipusing PUCCH format 1b, ACK/NACK for SPS may be mapped to an MSB of 2-bitACK/NACK (i.e. ACK/NACK for SPS is mapped to the first bit) and ACK/NACKfor the ‘one PDSCH with a PDCCH’ (e.g. a PDCCH with DAI=1) may be mappedto an LSB (i.e. ACK/NACK for PDSCH with PDCCH is mapped to the secondbit). Alternatively, even if the UE fails to detect a PDCCH (i.e. the‘PDCCH corresponding to a PDSCH’) when ACK/NACK for SPS is mapped to Iaxis and ACK/NACK for the ‘one PDSCH with a PDCCH’ (e.g. PDCCH withDAI=1) is mapped to the Q axis, the BS may receive an ACK/NACK responseto at least SPS transmission. This is because a constellation locationwhen ACK/NACK for the ‘SPS without a PDCCH’ is mapped to the I axis inthe case of failure of PDCCH detection is identical to a constellationlocation when the UE transmits an ACK/NACK response for ‘only’ the SPSwithout a PDCCH using BPSK constellation (i.e. I axis) using PUCCHformat 1a. Alternatively, a mapping relationship opposite to the aboveexample may be configured and mapping may be performed according toorder of received time.

In order to guarantee the BS to receive an ACK/NACK response for atleast SPS, it is possible to map specific information to a specificPUCCH resource in various ACK/NACK feedback transmission cases. Forexample, the channel selection mapping relationship may be configuredsuch that a PUCCH resource to which ACK/NACK for SPS transmission ismapped is identical to a PUCCH resource on which ACK/NACK for ‘only’ SPSis transmitted.

The following Table 15 shows modulation symbols (or constellation) forPUCCH formats 1a and 1b in legacy LTE release-8/9.

TABLE 15 PUCCH format b(0), . . . , b(M_(bit) − 1) d(0) 1a  0 1  1 −1  1b 00 1 01 −  j 10 j 11 −1  

In Table 15, it is assumed that a value ‘0’ of b(0) is NACK and ‘1’ isACK. Then, a value ‘00’ of b(0),b(1) denotes ACK/ACK and ‘11’ denotesNACK/NACK. In this case, at least one preceding bit b(0) has the samemodulation symbol as in PUCCH formats 1a and 1b. In other words, b(0) isalways 0 in both PUCCH formats 1a and 1b when d(0)=1 and is always 1 inboth PUCCH formats 1a and 1b when d(0)=−1. Accordingly, the BS mayreceive and detect information about at least one preceding bit b(0)even through the BS does not know whether received ACK/NACK feedback istransmitted using PUCCH format 1a or PUCCH format 1b. A channelselection mapping relationship may be configured such that ACK/NACK forthe ‘SPS without a PDCCH’ uses a PUCCH resource mapped to one precedingbit b(0). Therefore, the BS can guarantee reception of ACK/NACK for atleast SPS.

For example, when M=2, a channel selection mapping relationship shown inthe following Table 16 may be used.

TABLE 16 HARQ-ACK(0), HARQ-ACK(1) n_(PUCCH) ⁽¹⁾ b(0)b(1) ACK, ACKn_(PUCCH,1) ⁽¹⁾ 1, 0 ACK, NACK/DTX n_(PUCCH,0) ⁽¹⁾ 1, 1 NACK/DTX, ACKn_(PUCCH,1) ⁽¹⁾ 0, 1 NACK, NACK/DTX n_(PUCCH,0) ⁽¹⁾ 0, 0 DTX, NACK/DTXNo Transmission

In Table 16, ACK/NACK for SPS is mapped to HARQ-ACK(0) and ACK/NACK for‘PDSCH with a PDCCH’ may be mapped to HARQ-ACK(1).

For example, it is assumed that only the SPS having one codeword isreceived and the ‘PDSCH with a PDCCH’ is not received. In this case, anACK/NACK response to the SPS may be transmitted using PUCCH format 1a.

Meanwhile, when the ‘PDSCH with a PDCCH’ is received together with theSPS, channel selection according to the present invention may be used.In this case, a PUCCH resource indicated through an SPS activation PDCCHout of a higher-layer configured PUCCH resource set for the SPS may beused as n_(PUCCH,0) ⁽¹⁾ of Table 16. In addition, a PUCCH resourcederived (implicitly by a predetermined rule) from a CCE index of the‘PDCCH corresponding to a PDSCH’ may be used as n_(PUCCH,1) ⁽¹⁾ of Table16. In this case, the BS should be capable of receiving an ACK/NACKresponse to the SPS irrespective of whether the UE misses the ‘PDCCHcorresponding to a PDSCH’.

As described above, if the UE transmits an ACK/NACK response to the SPS,n_(PUCCH,0) ⁽¹⁾ is used. Here, ACK corresponds to a modulation symbol inwhich b(0)=1 and d(0)=−1 and NACK corresponds to a modulation symbol inwhich b(0)=0 and d(0)=1. Meanwhile, when the UE transmits ACK/NACKresponses to the SPS and the ‘PDSCH with a PDCCH’, a resource on whichan ACK/NACK response to the SPS may be confirmed in Table 16. The casesof ‘ACK, NACK/DTX’ and ‘NACK, NACK/DTX’ using n_(PUCCH,0) ⁽¹⁾ in Table16 will now be described. ‘ACK, NACK/DTX’ corresponds to a modulationsymbol in which b(0)b(1)=1 and d(0)=1 and ‘NACK, NACK/DTX’ correspondsto a modulation symbol in which b(0)b(1)=00 and d(0)=1. In summary, inboth of transmission of an ACK/NACK response for only the SPS andtransmission of ACK/NACK responses for the SPS and the ‘PDSCH with aPDCCH’, an ACK/NACK response for the SPS in ACK/NACK transmission usingn_(PUCCH,0) ⁽¹⁾ is transmitted through the same modulation symbol (i.e.d(0)=−1 for ACK and d(0)=1 for NACK). Accordingly, the BS may confirm anACK/NACK response for at least SPS upon detecting a signal onn_(PUCCH,0) ⁽¹⁾ irrespective of whether the BS has received an ACK/NACKresponse for the SPS or ACK/NACK responses for the SPS and the ‘PDSCHwith a PDCCH’.

Meanwhile, in the case of ‘ACK, ACK’ and the case of ‘NACK/DTX, ACK’ inTable 16, an ACK/NACK response may be transmitted using a resourcederived from a CCE index of the ‘PDCCH corresponding to a PDSCH’, i.e.using n_(PUCCH,1) ⁽¹⁾. Upon receiving a signal on n_(PUCCH,1) ⁽¹⁾, theBS may confirm that an ACK/NACK response to the ‘SPS without a PDCCH’and the ‘PDSCH with a PDCCH’ is received.

In the above example, while PUCCH format 1a has been described forconvenience, the same principle of the present invention may be appliedto PUCCH format 1b.

For example, an ACK/NACK response to ‘only’ the SPS having two codewordsmay be transmitted using PUCCH format 1b. Meanwhile, when the ‘PDSCHwith a PDCCH’ is received along with the SPS, spatial bundling may beused according to the example of the present invention. In the above twocases, ACK/NACK information for the SPS is transmitted through the samechannel (PUCCH resource) and modulation symbol. More specifically,ACK/ACK, ACK/NACK, NACK/ACK, and NACK/NACK for two codewords of the SPSbecome ACK, NACK, NACK, and NACK by applying spatial bundling (e.g.logical product). If ACK/NACK responses to the SPS and the ‘PDSCH with aPDCCH’ are simultaneously transmitted, the ACK/NACK response to the SPSbecomes ACK or NACK according to a spatial bundling result and theresponses are the same as ACK/NACK and NACK/NACK, respectively, of achannel and modulation symbol used for an ACK/NACK response to only theSPS. Therefore, upon detecting a signal n_(PUCCH,0) ⁽¹⁾, the BS mayconfirm an ACK/NACK response as a spatial bundling result according towhether a preceding signal (e.g. b(0)) for at least the SPS is ACK orNACK, irrespective of whether the BS has received an ACK/NACK responseto the SPS or ACK/NACK responses for the SPS and the ‘PDSCH with aPDCCH’.

The above constellation mapping may be identically applied to the casewhere the transmission mode in each cell is MIMO mode and the othercases. The constellation mapping may also be applied irrespective ofwhether spatial bundling is actually applied (i.e. irrespective ofwhether 2-codeword transmission is present).

In applying Embodiment 8-3, spatial bundling may be applied to ACK/NACKfeedback transmission even for ‘only’ the SPS without a PDCCH. Comparedwith Embodiment 8-1 or 8-2, this case can reduce the number of regionsin which blind decoding should be performed by the BS. Morespecifically, in a channel selection scheme defined in LTE release-8, achannel selection scheme for M of a large value is comprised of asuperset of a channel selection scheme for M of a small value. Forexample, transmission of one preceding bit (e.g. b(0)) or only ACK/NACKin channel selection of M=2 has the same result as transmission of 1-bitACK/NACK using PUCCH format 1a without applying channel selection.Accordingly, when a PUCCH format 1a/1b resource index indicated throughan SPS activation PDCCH for ACK/NACK for ‘only’ the SPS is used as afirst resource index used for channel selection, it is possible todistinguish between the case in which channel selection is used and thecase in which channel selection is not used. In this case, ACK/NACKresponses to the ‘SPS without a PDCCH’ and the ‘PDSCH with a PDCCH’ aredetected, an ACK/NACK response for ‘only’ the SPS is automaticallydetected. Accordingly, the BS may perform blind decoding in two regionsfor ACK/NACK detection (including ACK/NACK detection for ‘only’ the SPS)on a PUCCH format 1a/1b resource for channel selection and for ACK/NACKdetection on a PUCCH format 3.

Hereinafter, detailed application examples of Embodiment 8-3 will bedescribed.

Embodiment 8-3-1

As described above, an ACK/NACK response is generated with respect tothree cases. Case 1 relates to a PDSCH with a corresponding PDCCH, Case2 relates to a PDCCH indicating DL SPS release, and Case 3 relates to aPDSCH without a corresponding PDCCH. Case 3 is also referred to asACK/NACK for an SPS PDSCH.

In description of this embodiment, a ‘PDCCH’ related to an ACK/NACKresponse indicates Case 1 or Case 2 and an ‘SPS PDSCH’ indicates Case 3.An operation in which a specific UE performs DL reception for the abovethree cases and performs ACK/NACK for DL reception. An ACK/NACK responsetransmitted in an n-th UL subframe has a relationship of an ACK/NACKresponse to DL transmission for the above three cases in an (n-k)-thsubframe(s) (where kεK and K: k₀, k₁, . . . k_(M-1) and see Table 12).Description of an ACK/NACK transmission subframe location will beomitted hereinbelow.

In this embodiment, to support dynamic transmit power caused by a TPCcommand without lowering performance, a predefined channel selectionscheme (defined in LTE release-8 or release-10) through PUCCH format 1amay be used.

The case in which one serving cell is configured will now be describedfirst.

In this case, use of a TPC field is determined as follows.

A (2-bit) TPC field in a PDCCH in which DL DAI=1 is used for a TPCcommand of an original purpose.

A (2-bit) TPC field in a PDCCH in DL DAI>1 is used for an ARI purpose.The UE assumes that, in all PDCCHs in which DL DAI>1, ARI values are thesame.

In addition, the use of a PUCCH format is determined as follows.

If the UE receives only an SPS PDSCH, an LTE release-8 PUCCH format1a/1b resource is used (i.e. operation in fallback mode).

If the UE receives one PDCCH in which DL DAI=1, an LTE release-8 PUCCHformat 1a/1b resource is used (i.e. operation in fallback mode).

If the UE receives an SPS PDSCH and an additional PDCCH with DL DAI=1, apredefined channel selection scheme through PUCCH format 1a (a channelselection scheme defined in LTE release-8 or release-10) is used. Here,a first PUCCH resource is determined by higher layer configuration (e.g.by a resource indicated by an ARI of an SPS PDCCH out of an RRCconfigured resource set) and a second PUCCH resource is determined basedon a number (or index) of a first CCE used for transmission of acorresponding PDCCH (i.e. a PDCCH in which DL DAI=1).

In the other cases, PUCCH format 3 is used as a configured PUCCH format.

Meanwhile, the case in which more than one serving cell is configuredwill now be described.

Here, the use of a TPC field is determined as follows.

A (2-bit) TPC field in a PDCCH in which DL DAI=1 only on a PCell is usedfor a TPC command of an original purpose.

A (2-bit) TPC field of each of all other PDCCH(s) on the PCell andSCell(s) is used for a TPC command of an original purpose. The UEassumes that, in all PDCCH(s) on the PCell and SCell(s), ARI values arethe same.

In addition, the use of a PUCCH format is determined as follows.

If the UE receives only an SPS PDSCH, an LTE release-8 PUCCH format1a/1b resource is used (i.e. operation in fallback mode).

If the UE receives one PDCCH in which DL DAI=1, an LTE release-8 PUCCHformat 1a/1b resource is used (i.e. operation in fallback mode).

If the UE receives an SPS PDSCH and an additional PDCCH in which DLDAI=1 only on the PCell, a predefined channel selection scheme throughPUCCH format 1a (a channel selection scheme defined in LTE release-8 orrelease-10) is used. Here, a first PUCCH resource is determined byhigher layer configuration (e.g. by a resource (see Table 14) indicatedby an ARI of an SPS activation PDCCH out of an RRC configured resourceset) and a second PUCCH resource is determined based on a number (orindex) of a first CCE used for transmission of a corresponding PDCCH(i.e. a PDCCH in which DL DAI=1).

In the other cases, PUCCH format 3 is used as a configured PUCCH format.

Embodiment 8-3-2

In description of this embodiment, a ‘PDCCH’ related to an ACK/NACKresponse indicates Case 1 or Case 2 and an ‘SPS PDSCH’ indicates Case 3,as described in the above Embodiment 8-3-1. The term ‘PDSCH with DAI=1’or ‘PDSCH with DL DAI>1’ refers to a DL DAI indicated by a PDCCHcorresponding to the PDSCH is 1 or is greater than 1. Description of anACK/NACK transmission subframe location will be omitted hereinbelow.

If the UE receives an SPS PDSCH and a PDSCH with DL DAI=1, since thereis no ARI information, the UE cannot be aware of available PUCCHresources. To solve this problem, the following methods may beconsidered.

The case in which channel selection of M=2 in LTE release-8 is used willnow be described first.

If the UE receives only an SPS PDSCH and a PDSCH with DL DAI=1 and doesnot receive a PDSCH with DL DAI>1, the UE transmits ACK/NACK by TDDchannel selection of M=2 in LTE release-8 while applying spatialbundling for the PDSCHs. When LTE release-8 TDD channel selection isused, the UE transmits two ACK/NACK bits. Here, one of a channelselection mapping relationship in LTE release-8 (e.g. the above Tables 5to 7) and a channel selection mapping relationship in LTE release-10(e.g. the above Tables 8 to 11) may be used and this may be determinedby RRC configuration.

In applying LTE release-8 channel selection, a value of n_(PUCCH,1) ⁽¹⁾is determined by an SPS PUCCH resource (i.e. a resource indicated by anSPS activation PDCCH of a higher-layer configured resource set, seeTable 14). In addition, HARQ-ACK(0) is an ACK/NACK/DTX response to SPSPDSCH transmission. This is to solve ambiguity for the case in which theUE misses a PDSCH with DAI=1 and an ACK/NACK response to SPStransmission can be certainly transmitted.

In this case, a TPC field of a PDCCH with DL DAI=1 may be actually usedfor PUCCH power control. However, in a cell supporting MIMO transmission(or 2-codeword transmission), loss of an ACK/NACK bit may occur due tospatial bundling for a PDSCH with DAI=1 may occur.

Meanwhile, the case in which PUCCH format 3 is used may be considered.

If the UE receives both an SPS PDSCH and a PDSCH with DL DAI=1, the UEmay assume that a TPC field of a PDCCH with DL DAI=1 is used for an ARIpurpose. Then, the UE may transmit 2-bit ACK/NACK (on a non-MIMO cell)or 3-bit ACK/NACK (on a MIMO cell) using PUCCH format 3.

In this case, since ACK/NACK bundling is not applied, ACK/NACK bits maybe transmitted without loss of ACK/NACK information. Meanwhile, since aTPC field used for an original TPC command purpose is not present (sincea TPC field of a PDCCH with DL DAI=1 is used for an ARI purpose), PUCCHpower control may not be correctly performed.

In consideration of this fact, the following two methods are proposedfor resource allocation for TDD PUCCH format 3 in CA.

The first method is to reuse resource allocation for FDD PUCCH format 3in CA. In this case, a TPC field(s) on a PCell may be used for anoriginal purpose and a TPC field(s) on an SCell(s) may be used for anARI purpose. If the UE receives PDSCHs only on the PCell, ACK/NACKbundling defined in LTE release-8 may be used.

The second method is to reuse resource allocation for TDD PUCCH format 3when CA is not supported (i.e. in non-CA). Then, a TPC field of a PDCCHwith DAI=1 on a PCell may be used for an original purpose and TPC fieldsof all other PDCCHs on the PCell and SCells may be used for an ARIpurpose. When the UE receives an SPS PDSCH or a PDSCH with DL DAI=1 onlyon the PCell, LTE release-8 PUCCH format 1a/1b may be used (i.e.fallback mode operation). When the UE receives an SPS PDSCH and a PDSCHwith DL DAI=1 but does not receive PDSCHs with DL DAI>1, LTE release-8channel selection is used.

ACK/NACK Transmission Through PUCCH in TDD System

An ACK/NACK bundling method and a resource allocation method in LTE-A(or LTE release-10) are described.

For ACK/NACK feedback in TDD using PUCCH format 3, mode 1 and mode 2 aredefined. Mode 1 may support an ACK/NACK payload size of up to 20 bits.If the number of indicated ACK/NACK bits exceeds 20, spatial bundling isused. If the number of ACK/NACK bits indicated in Mode 1 is less than20, no bundling is supported. Meanwhile, Mode 2 is a scheme in whichpartial bundling (bundling in a time domain or bundling in a CC domain)is applied along with spatial bundling. That is, in Mode 2, if thenumber of indicated ACK/NACK bits exceeds x, spatial bundling isperformed simultaneously with partial bundling.

When channel selection is applied to ACK/NACK feedback in TDD usingPUCCH format 1b, Mode a and Mode b are defined. Mode a is a scheme inwhich no bundling is supported when the number of indicated ACK/NACKbits is less than 4. Mode b is a scheme in which partial bundling(bundling in a time domain or bundling in a CC domain) is applied alongwith spatial bundling when the number of indicated ACK/NACK bits exceeds4.

On the other hand, resource allocation for PUCCH format 3 is defined asfollows. A (2-bit) TPC field in a PDCCH corresponding to a PDSCH on aPCell is used for a TPC command of an original purpose. A (2-bit) TPCfield of a PDCCH corresponding to a PDSCH on an SCell is used for an ARIpurpose. If a PDCCH corresponding to a PDSCH on an SCell is not receivedand a PDSCH on a PCell is received, PUCCH format 1a/1b is used by ascheme defined LTE release-8.

Hereinafter, when DL reception is present only on a PCell, an ACK/NACKbundling method and a resource allocation method will be described.

Embodiment 9

Embodiment 9 relates to spatial bundling in Mode 1.

Mode 1 for TDD may support individual ACK/NACK transmission of up to 20bits. However, if the number of indicated ACK/NACK bits exceeds 20,spatial bundling needs to be applied. Since individual ACK/NACKinformation is not sure to be fed back when spatial bundling is applied,efficiency of a HARQ operation may be reduced and thus it is necessaryto maximally transmit individual ACK/NACK information without bundling.That is, simple application of spatial bundling to all ACK/NACK bits isnot desirable in terms of DL throughput performance. Moreover, sinceMode 1 is a scheme for transmitting individual ACK/NACK feedback withoutchange, spatial bundling should be minimally applied. Therefore, spatialbundling needs to be performed such that the number of ACK/NACK bits isnearest 20 but less than 20.

A detailed method for performing spatial bundling when the numberindicated ACK/NACK bits exceeds 20 will be described hereinbelow.

As a first method, spatial bundling in the unit of CCs (CC-wise) may beconsidered. According to the first method, spatial bundling may beapplied over all DL subframes in one specific CC. In this way, spatialbundling may be performed throughout all subframes with respect to otherCCs until the number of ACK/NACK bits to be actually transmitted is lessthan 20. Assuming that a PCell is more frequently scheduled relative toan SCell, spatial bundling may be applied lastly on the PCell.

When TTD is configured as 9DL:1UL (i.e. configuration for transmittingACK/NACK for DL transmission in 9 DL subframes is transmitted in one ULsubframe, e.g. see subframe 2 of UL-DL configuration 5 of Table 12), ifthe number of configured CCs exceeds 2, an ACK/NACK payload size exceeds20 bits even though spatial bundling is applied to all CCs. Accordingly,when the number of configured CCs is 2, spatial bundling may be appliedto all CCs.

When TDD configuration is not 9DL:1UL, spatial bundling is applied toN_(configuredDLsubframe)+N_(CW) _(—) _(SF)−9 CC(s) having two configuredcodewords starting from a CC having the last index (or highest index) ona logical index. Spatial bundling may be applied lastly to the PCell(i.e. the lowest logical index may be assigned to the PCell). Here,N_(configuredDLsubframe) is the number of DL subframes in which ACK/NACKis fed back on one CC. N_(CW) _(—) _(SF) is the total number ofcodewords for which ACK/NACK is fed back in one subframe on all DL CCs.That is, N_(CW) _(—) _(SF) may be determined as indicated by Equation 2.

$\begin{matrix}{N_{CW\_ SF} = {\sum\limits_{i = 0}^{N_{{configured}\mspace{14mu}{CCs}} - 1}\; N_{{CW},i}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In Equation 2, N_(CW,i) is the number of codewords configured on an i-thCC.

As a second method, spatial bundling in the unit of subframes(subframe-wise) may be considered. According to the second method,spatial bundling may be applied over all CCs in one specific DLsubframe. In this way, spatial bundling may be performed throughout allCCs with respect to other DL subframes until the number of ACK/NACK bitsto be actually transmitted is less than 20.

According to the aforementioned first or second method, the number ofbundled ACK/NACK bits is 18, 19, or 20. According to the number of CCsconfigured for the UE, the number of ACK/NACK bits when the first orsecond method is applied is shown in the following Table 17.

TABLE 17 No. of configured CCs Option 1 Option 2 2 18, or 18 18, or 18 320 18 4 20, 18, 20, 18, or 20 20, 18, 19, 20, or 20 5 20, 18, 20, 18,20, 18, 20, 19, 20, 18, 20, 19, 20, 18, or 20 20, 20, or 20

The first method may maximally support individual ACK/NACK transmissionfor a PCell relative to the second method and may be simply expressed.If the number of indicated ACK/NACK bits exceeds 20, it is preferable toperform spatial bundling in CC-wise (i.e. to apply the first method).

Embodiment 10

In Embodiment 10, a detailed application example of the aforementionedMode 2 and Mode b is described. Mode 2 is a scheme in which partialbundling (bundling in a time domain or bundling in a CC domain) isapplied along with spatial bundling for ACK/NACK feedback in TDD usingPUCCH format 3. Mode b is a scheme in which partial bundling (bundlingin a time domain or bundling in a CC domain) is applied along withspatial bundling for ACK/NACK feedback in TDD using PUCCH format 1b,when channel selection is applied in the case in which the number ofindicated ACK/NACK bits exceeds 4.

Mode 2 may be favorably applied to improve ACK/NACK performance withrespect to a power-limited UE. When comparing FDD supporting ACK/NACK ofup to 10 bits with TDD supporting ACK/NACK of up to 20 bits, TDD hasless UL coverage than FDD. In addition, Mode 1 (in which spatialbundling is applied when the number of indicated ACK/NACK bits exceeds20 and spatial bundling is not applied when the number of indicatedACK/NACK bits is 20 or less) cannot support ACK/NACK feedback when thenumber of DL CCs exceeds 2 in TDD 9DL-1UL configuration. For example, tosupport ACK/NACK feedback on 5 DL CCs and in the TDD 9DL-1ULconfiguration, a total of 45 ACK/NACK bits are needed even if spatialbundling is applied. Accordingly, to support ACK/NACK feedback in atleast TDD 9DL-1UL configuration, it is necessary to support theabove-mentioned Mode 2 for PUCCH format 3.

Hereinafter, spatial bundling applied to Mode 2 and Mode b will bedescribed in detail.

Embodiment 10-1

In Embodiment 10-1, spatial bundling in a time domain is described.Time-domain bundling in this embodiment may be performed in addition tospatial bundling.

Time-domain bundling as spatial bundling may be performed withoutadditionally modifying a 2-bit DAI defined in LTE release-8 on each CC.Further, in applying time-domain bundling, time-domain bundling may besimply applied on each CC without the need to consider various forms ofCA. That is, it is sufficient to determine one time-domain bundlingmethod for various cases of CA. Since the size of ACK/NACK informationbits which are an application result of time-domain bundling is 10 bits,a PUCCH format 3 structure of LTE release-10 may be used as a PUCCHformat to be used for ACK/NACK transmission.

A DAI value is sequentially increased with respect to allocated PDCCHs.Therefore, when a DAI is used, a UE cannot recognize the case of missingthe last PDCCH in a time-domain bundling window. To solve this problem,a DAI value for the last detected PDCCH on each CC may be input to anACK/NACK mapper and then encoded.

FIG. 40 is a diagram illustrating exemplary time-domain partialbundling. In the example of FIG. 40, ACK/NACK bundling is applied over 4subframes on each CC.

In the first CC of FIG. 40, the UE has received a PDCCH with DAI=0 inthe first subframe and a PDCCH with DAI=1 in the second subframe but hasnot received a PDCCH with DAI=2 in the third subframe. Then, since theUE does not know whether the last PDCCH (DAI=2) has been transmitted,the UE may recognize that all PDCCHs in a time-domain bundling windowhave been received. In addition, FIG. 40 shows the case in which each ofPDSCHs scheduled by the received PDCCHs is successfully decoded (i.e.ACK) and, as a result, ACK is generated as bundled ACK/NACK information.Together with the generated ACK information, the UE may encode the lastreceived DAI value, i.e. DAI=1. The UE encodes and transmits ACK and DAI(DAI=1) and then the BS may recognize that the UE misses a PDCCH(DAI=2).

The time-domain bundling operation on the second CC of FIG. 40 issimilar to that on the first CC. The UE may encode a last received DAIvalue (i.e. DAI=0) together with ACK information. Since the UE encodesand transmits ACK and a DAI (DAI=0), the BS may recognize that the UEmisses a PDCCH (DAI=1).

In the third CC of FIG. 40, the UE receives a PDCCH (DAI=0) in the firstsubframe and receives a PDCCH (DAI=2) in the third subframe. Even thoughthe UE does not recognize transmission of PDCCH (DAI=1) in the secondsubframe, the UE may recognize that itself misses a PDCCH (DAI=1)because DAI values of received PDCCHs are not sequentially increased.Although FIG. 40 shows the case in which each of PDSCHs scheduled by thereceived PDCCHs is successfully decoded (i.e. ACK), the UE may generateNACK as bundled ACK/NACK information because transmission of one PDCCHis missed.

In the fourth CC of FIG. 40, the UE receives only a PDCCH (DAI=0) andgenerates ACK information upon successfully decoding a PDSCH scheduledby the PDCCH. The generated ACK information may be encoded together withthe last received DAI value (DAI=0).

In the fifth CC of FIG. 40, the UE receives only a PDCCH with DAI=0. TheUE does not know that a PDCCH with DAI=1 has been transmitted in thefourth subframe. FIG. 40 shows the case in which a PDSCH scheduled by aPDCCH received by the UE is not successfully decoded (i.e. NACK).Accordingly, the UE may generate NACK information.

Thus, when time-domain spatial bundling is applied, a (2-bit) TDD DAI ofLTE release-8 may be reused (i.e. as a PDCCH accumulation counter) oneach CC without modification.

As an example of PUCCH format 3 for application of Mode 2, an ACK/NACKstate per CC before channel coding may be defined as indicated in Table18.

TABLE 18 Bundled ACK/NACK with DAI value of the A/N states per CC lastreceived PDCCH [information bits] ACK w DAI = 0 or 3 00 ACK w DAI = 1 01ACK w DAI = 2 10 NACK w any DAI 11

A result of bundled ACK/NACK encoded together with a DAI value of a lastreceived PDCCH on each CC in FIG. 40, using the ACK/NACK state of Table18, is expressed as follows: ‘01 (DAI=1)’ on the first CC, ‘01 (DAI=0)’on the second CC, ‘11 (NACK)’ on the third CC, ‘00 (DAI=0)’ on thefourth CC, and ‘11 (NACK)’ on the fifth CC.

An aggregate of ACK/NACK payloads for five CCs before channel coding isperformed in PUCCH format 3 to which Mode 2 is applied is ‘0100110011’.

The principle of the present invention for the above-described Mode 2may be identically applied to Mode b. For application to Mode b, arelationship between a channel selection mapping relationship (a mappingrelationship between a PUCCH resource and ACK/NACK bits) and a NACK/DAIvalue may be defined.

Accordingly, when time-domain bundling is used, each ACK/NACK responseon each CC may be expressed as bundling ACK/NACK information.

Embodiment 10-2

In Embodiment 10-2, CC-domain partial bundling is described. Time-domainbundling in this embodiment may be performed in addition to spatialbundling.

In CC-domain bundling, it is preferable to use a DAI as an indicatorindicating the total number of scheduled PDSCHs (or correspondingPDCCHs) in a bundling window comprised of a plurality of CCs in onesubframe, rather than a DAI as an accumulation counter of scheduledPDSCHs (or corresponding PDCCHs) in a plurality of subframes on each CCas in a conventional DAI. This is because, when the DAI indicates thetotal number of PDSCHs (or PDCCHs) per subframe, there is no need toprovide a solution for the case in which the UE misses the last PDCCH intime.

Then, the UE may transmit ACK when the number of ACKs generated forsuccessfully decoded DL transmission in a bundling window is equal tothe total number of PDSCHs (or PDCCHs) in the bundling window and,otherwise, the UE transmits NACK (at this time, DTX is expressed asNACK).

Hereinafter, application of CC-domain bundling to Mode b and Mode 2 willbe described in detail.

Channel selection for application of CC-domain bundling to Mode b isdescribed with reference to FIG. 41.

In this case, it is basically assumed that a channel selection mappingrelationship of LTE release-10 (e.g. the above Tables 8 to 11) isapplied.

If an ACK/NACK PUCCH resource which is implicitly determined (i.e.derived from a CCE index of a PDCCH) is used, a PUCCH resource linkeddynamically with a PDCCH for scheduling on a PCC (or PCell) may beselected first in each subframe.

If PDSCHs are scheduled only on a PCC (or PCell) in a multi-CCconfiguration, ACK/NACK resource mapping in LTE release-8 (e.g. theabove Tables 5 to 7) may be applied. That is, an operation of fallbackmode in LTE release-8 may be performed.

In the example of FIG. 41, it is assumed that two cells (a PCC and anSCell) are configured in each subframe.

In a TDD 2DL:1UL configuration of FIG. 41, in the first subframe, sincea PDSCH is not scheduled on a PCC and is scheduled on an SCC, a PUCCHresource is determined from a CCE index of a PDCCH for scheduling theSCC PDSCH. In the second subframe, a PUCCH resource may be determinedfrom a CCE index of a PDCCH for scheduling a PCC PDSCH. A channelselection operation may be used using such PUCCH resources. For example,ACK/NACK transmission may be performed using the channel selectionmapping relationship as shown in Table 8.

In a TDD 3DL:1UL configuration, PDSCHs are scheduled only on a PCC inall subframes. In this case, a fallback mode operation may be performedas described above. For example, ACK/NACK transmission may be performedthrough PUCCH format 1b using the channel selection mapping relationshipas shown in Table 6.

In a TDD 4DL:1UL configuration, since PDSCHs are scheduled on both a PCCand an SCC in the first subframe, PUCCH resources may be determinedbased on a CCE index of a PDCCH for scheduling a PDSCH on the PCC. Sincea PDSCH is not scheduled in the second subframe and is scheduled only onone cell (PCC or SCC) in the third and fourth subframes, PUCCH resourcesmay be determined based on a CCE index of PDCCHs of the correspondingPDSCHs. In this way, a channel selection operation may be performedusing the determined PUCCH resources. For example, ACK/NACK transmissionmay be performed using the channel selection mapping relationship shownin Table 10.

An example of applying CC-domain bundling to Mode 2 is described withreference to FIG. 42.

In the example of FIG. 42, it is assumed that the maximum number ofACK/NACK bits is 12 and a maximum bundling window is 2 (i.e. a maximumof two CCs is included in one bundling window).

To keep individual ACK/NACK transmission, bundling is gradually applieduntil the number of ACK/NACK bits is nearest 12 and less than 12.

In addition, a PCell (or PCC) is not included in a bundling window. Thatis, the bundling window is configured for only SCells (SCCs). Thebundling window may be applied in ascending order of CC index.

As illustrated in FIG. 42, CC-domain bundling may gradually apply abundling window (comprised of 2 CCs) until the number of ACK/NACK bits(the number of ACK/NACK bits after spatial bundling is applied) becomes12 or less.

In a 2DL:1UL configuration of FIG. 42, since the number ACK/NACK bitsafter spatial bundling is performed is 10, the bundling window is notconfigured.

In a 3DL:1UL configuration, since the number ACK/NACK bits after spatialbundling is performed is 15, a bundling window is configured. The numberof ACK/NACK bits after the bundling window for two CCs (SCC3 and SCC4)is configured is 12 and, therefore, the bundling window is notconfigured any more.

In a 4DL:1UL configuration of FIG. 42, since the number of ACK/NACK bitsafter spatial bundling is performed is 20, a bundling window isconfigured. When a bundling window for two CCs (SCC3 and SCC4) isconfigured, a 16-bit ACK/NACK is generated and thus an additionalbundling window is configured. If the additional bundling window isconfigured for two CCs (SCC1 and SCC2), 12-bit ACK/NACK is generatedand, therefore, a bundling window is not configured any more.

Accordingly, when CC-domain partial bundling is used, a bundling resultfor all ACK/NACK bits in the bundling window (e.g. a result of logicalAND operation) is transmitted as ACK/NACK information. A DAI in a PDCCHindicates the total number of PDSCHs scheduled on all CCs in onesubframe. A maximum size of the bundling window for PUCCH format 3 maybe determined as 2 (i.e. a maximum of two CCs (or cells) may configureone bundling window).

Embodiment 11

Embodiment 11 relates to an ACK/NACK transmission method through PUCCHformat 3 when PDCCH/PDSCH is received only on a PCell (hereinafter,referred to as PCell-only-receiving). Especially, PCell-only-receivingin TDD is described in detail.

When a PDCCH corresponding to a PDSCH is not received on SCells and isreceived only on a PCell, a PUCCH format 1a/1b resource of LTE release-8may be used (i.e. may operate in fallback mode).

In FDD, the fallback mode may be applied for the purpose of using aPUCCH resource defined in LTE release-8 and the purpose of definitelydetermining the PUCCH resource even without receiving an ARI on SCells.

If a TPC field is used for an ARI purpose on SCells, an ACK/NACKresource may be ambiguous in a PCell-only-receiving case. To solve sucha problem, ACK/NACK multiplexing or ACK/NACK bundling defined in an LTErelease-8 TDD system may be applied. However, if ACK/NACK bundling ortime domain bundling is applied, some ACK/NACK information cannot betransmitted and, therefore, substantial loss of DL throughput may begenerated. Further, since partial ACK/NACK states are overlapped in anACK/NACK mapping relationship, ACK/NACK performance for 4-bit ACK/NACKin an LTE release-8 TDD system cannot be guaranteed.

Accordingly, an ACK/NACK transmission method for a PCell-only-receivingcase is proposed hereinbelow.

Embodiment 11-1

According to this embodiment, a resource of PUCCH format 1a/1b definedin LTE release-8 may be used when a single PDSCH is received on a PCell.In this case, use of a DAI and an ARI may be defined as follows.

FIG. 43 is a diagram illustrating an example of use of a DAI and a TPC.

As illustrated in FIG. 43, DAIs on a PCell may be used as anaccumulation counter of a PDCCH (or PDSCH) as in an LTE release-8 TDDsystem. DAIs on SCells may be used as an accumulation counter of a PDCCH(or PDSCH) as in an LTE release-8 TDD system. The DAIs on SCells may beconfigured as ‘00’. In the illustrated example of FIG. 43, DAI values ofPDCCHs of SCells are all configured as ‘00’. If the DAI values of PDCCHson SCells are configured identically as ‘00’, PDCCH DCI may also bescheduled even in a common search space. The predefined value of ‘00’may be used as a virtual CRC (i.e. for error detection when a DAI valueis not ‘00’) in terms of UE implementation.

As illustrated in FIG. 43, a TPC field of a PDCCH allocated first on aPCell (i.e. a PDCCH with DAI=00) is used for a TPC command of anoriginal purpose. TPC fields of all other PDCCHs (including the PCelland SCells), except for the PDCCH with DAI=00 on the PCell, are used foran ARI purpose. Fields used for the ARI purpose in the PDCCHs shouldhave the same value in all PDCCHs.

UE behavior in this case may be defined as follows.

-   -   If there is PDSCH transmission without a corresponding PDCCH on        a PCell (i.e. only SPS PDSCH),        -   if there is no other PDSCH transmission,            -   LTE release-8 PUCCH format 1a/1b is used.        -   Else,            -   PUCCH format 3 is used.                -   Exceptionally, a TPC field in a PDCCH with DAI=‘00’                    is used as an ARI.    -   Else,        -   if there is a single PDSCH with DAI=‘00’ on a PCell or there            is a single PDCCH with DAI=‘00’ indicating DL SPS release on            a PCell,            -   LTE release-8 PUCCH format 1a/1b is used.        -   Else,            -   PUCCH format 3 is used.

In the above description, the case where ‘there is PDSCH transmissionwithout a corresponding PDCCH’ corresponds to a DL SPS PDSCH. Moreover,‘a single PDSCH with DAI=‘00’ indicates that a DAI field in a PDCCHcorresponding to the PDSCH is 00.

Embodiment 11-1 is applicable to all cases including a 9DL:1UL subframeconfiguration for TDD ACK/NACK feedback and time-domain/CC-domainbundling for Mode 1 and Mode 2.

The above-described Embodiment 11-1 is summarized as follows.

Resources of LTE release-8 PUCCH format 1a/1b and PUCCH format 1a/1b areused in (1) the case where there is ‘a single PDSCH without acorresponding PDCCH’ on a PCell, (2) the case where there is ‘a singlePDSCH with a corresponding PDCCH’ only on a PCell and a DAI value in thePDCCH is 00, or (3) the case where there is ‘a single PDCCH indicatingDL SPS release’ only on a PCell and a DAI value in the PDCCH is 00.

LTE release-8 PUCCH format 3 is used for cases except for the above (1),(2), and (3) cases.

If there is no ‘PDSCH without a corresponding PDCCH (i.e. DL SPS PDSCH)’on a PCell, the following operation is performed. If there is a ‘PDSCHwith a corresponding PDCCH’ on the PCell and a DAI value of the PDCCH is00, a TPC field of the PDCCH is used for an actual TPC command. If thereis a ‘PDCCH indicating DL SPS release’ and a DAI value of the PDCCH is00, a TPC field of the PDCCH is used for an actual TPC command. In theother cases, all TPC fields are used as ARIs.

In the other cases (i.e. there is a ‘PDSCH without a corresponding PDCCH(i.e. DL SPS PDSCH) on a PCell), all TPC fields of PDCCHs are used asARIs.

In addition, in all of the above cases, all fields used as ARIs inPDCCHs have the same value.

Embodiment 11-2

In FDD, TPC fields on SCells are used for an ARI purpose and TPC fieldson a PCell are used for an original TPC purpose. According to thisembodiment, in TDD, TPC fields in PDCCHs on the PCell are used for anoriginal TPC purpose and TPC fields in PDCCHs on SCells are used for anARI purposes, in a similar manner as in FDD. In this case, the samePUCCH power control operation as an operation in legacy LTE release-8may be performed without modification.

FIG. 44 is a diagram illustrating another example of use of a DAI and aTPC.

As in the example of FIG. 44, DAI fields of PDCCHs on a PCell may beused for an ARI purpose with respect to a UE receiving PDSCHs only onthe PCell. Using such DAI fields is available in Mode 1 because Mode 1does not need to support a DAI in time-domain/CC-domain bundling. Inaddition, fields used as ARIs of PDCCHs (DAI fields on the PCell and TPCfields on SCells) should have the same value.

In the illustrated example of FIG. 44, DAI values of PDCCHs on theSCells are all configured as ‘00’. A description thereof is omittedbecause it is the same as that of FIG. 43.

UE behavior based on the above description is defined as follows.

-   -   For a PDCCH(s) which schedules a PDSCH(s) or indicate SPS        release on a PCell,        -   a TPC field is used for a TPC command.        -   A DAI field is used as an ARI for PUCCH format 3.    -   For PDCCHs which schedule PDSCHs on SCells,        -   a TPC field is used as an ARI for PUCCH format 3.    -   Exceptionally, for only an SPS PDSCH without a PDCCH,        -   LTE release-8 PUCCH format 1a/1b (RRC-configured for SPS) is            used.    -   All fields used as ARIs in PDCCHs have the same value.

The above embodiments 9 to 11 mainly relate to a detailed applicationexample of the present invention for ACK/NACK transmission through aPUCCH in a TDD system. In the following Embodiment 12, examples in whichthe present invention reusing a TPC field on a PCell as an ARI isapplied to FDD and TDD systems will be described in detail.

Embodiment 12

In this Embodiment 12, a method of using an ARI in a ‘PDCCH indicatingDL SPS release’ on a PCell is described.

Specifically, Embodiment 12 relates to a method for transmittingACK/NACK through PUCCH format 3 by reusing a TPC field of a ‘PDCCHindicating DL SPS release’, when a single ‘PDCCH indicating DL SPSrelease’ on a PCell is received in the case where there are no PDSCH onan SCell(s) and an SPS PDSCH (i.e. a PDSCH without a correspondingPDCCH) on the PCell. That is, the method for transmitting ACK/NACK whenthere is no SPS PDSCH (i.e. a PDSCH without a corresponding PDCCH) and asingle PDSCH is received on the PCell have been described. In thisembodiment, an additional ACK/NACK transmission method when a PDSCH (aPDSCH with/without a corresponding PDCCH) is not present and a ‘PDCCHindicating DL SPS release’ is received on the PCell is described.

A method of using an ARI in FDD is as follows.

A TPC field of a ‘PDCCH indicating DL SPS release’ on a PCell is usedfor an ARI purpose. A TPC field of a PDCCH except for the ‘PDCCHindicating DL SPS release’ is used on the PCell for a TPC command of anoriginal purpose. Further, a TPC field of a PDCCH on SCells is used asan ARI. The UE assumes that all ARI values on the PCell and SCells arethe same.

UE behavior based on the above description may be defined as follows.

-   -   If there is a single PDSCH without a corresponding PDCCH on a        PCell (i.e. only SPS PDSCH),        -   LTE release-8 PUCCH format 1a/1b is used.            -   A PUCCH resource may be selected from among                RRC-configured resources, by a TPC field of a PDCCH                corresponding to SPS or by a value of a TPC field in a                PDCCH during SPS activation when a corresponding PDCCH                is not present (explicit mapping).            -   When a corresponding PDCCH is present, a PUCCH resource                may be selected by a prescribed rule based on a CCE                index of the PDCCH (e.g. by an equation defined in LTE                release-8 (implicit mapping).    -   Else if there is a single PDCCH indicating DL SPS release only        on a PCell (i.e. only SPS release PDCCH).        -   PUCCH format 3 is used.        -   Exceptionally, a TPC field of a PDCCH indicating DL SPS            release may also be used as an ARI.    -   Else,        -   PUCCH format 3 is used.

Next, a method of using a DAI and an ARI in TDD is as follows.

A DAI on a PCell is used as an accumulation counter of PDCCHs/PDSCHs asin LTE release-8. DAIs for SCells are configured as a preset value (e.g.‘00’) so that DCI is scheduled on a common search space. The presetvalue may be used as a virtual CRC in terms of UE implementation.

A TPC field of a PDCCH allocated first on a PCell (i.e. a PDCCH withDAI=1 or DAI=00) is used for a TPC command of an original purpose. TPCfields of all other PDCCHs (i.e. the other PDCCHs on the PCell andPDCCHs on SCells) except for the PDCCH allocated first on the PCell areused for an ARI purpose. TPC fields when DAI=‘00’ in the above otherPDCCHs are also used as ARIs. In addition, the UE assumes that all ARIvalues are the same.

UE behavior based on the above description may be defined as follows.

-   -   If there is a PDSCH transmission on a PCell and there is no        PDCCH corresponding to the PDSCH (i.e. SPS PDSCH),        -   if there is no other PDSCH transmissions (i.e. if only an            SPS PDSCH is present),            -   LTE release-8 PUCCH format 1a/1b is used.            -   A PUCCH resource may be selected from among                RRC-configured resources, by a TPC field of a PDCCH                corresponding to SPS or by a value of a TPC field in a                PDCCH during SPS activation when a corresponding PDCCH                is not present (explicit mapping).                -   When a corresponding PDCCH is present, a PUCCH                    resource may be selected by a prescribed rule based                    on a CCE index of the PDCCH (e.g. by an equation                    defined in LTE release-8 (implicit mapping)).        -   Else if (i.e. if an SPS PDSCH includes other additional            transmissions),            -   PUCCH format 3 is used/            -   Exceptionally, a TPC field in a PDCCH with DAI=‘00’ is                also used as an ARI.    -   Else, no SPS        -   If there is a single PDSCH transmission only on PCell only            with DAI=‘00’, (only first PDCCH)            -   Rel-8 PUCCH format 1a/1b is used.                -   Implicit mapping may be used by a rule such as an                    equation in Rel-8 TDD based on a CCE index of the                    PDCCH.                -   A PUCCH resource may be selected from among                    RRC-configured resources, by a TPC field of a PDCCH                    corresponding to SPS or by a value of a TPC field in                    a PDCCH during SPS activation (when a corresponding                    PDCCH is not present) (explicit mapping).        -   Else if there is a single PDCCH only on PCell only            indicating downlink SPS release on PCell (only SPS release),            -   PUCCH format 3 is used.            -   As an exceptional case, the TPC field in PDCCH                indicating downlink SPS release is also used as ARI        -   Else,            -   PUCCH format 3 is used.

Embodiment 13

Embodiment 13 relates to a method of using different TPC fieldsaccording to whether an SPS PDSCH is present.

As described above, an ACK/NACK response is generated with respect tothree cases. Case 1 relates to a PDSCH with a corresponding PDCCH, Case2 relates to a PDCCH indicating DL SPS release, and Case 3 relates to aPDSCH without a corresponding PDCCH. Case 3 is also referred to asACK/NACK for an SPS PDSCH.

In description of this embodiment, a ‘PDCCH’ related to an ACK/NACKresponse indicates Case 1 or Case 2 and an ‘SPS PDSCH’ indicates Case 3.An operation in which a specific UE performs DL reception for the abovethree cases and performs ACK/NACK for DL reception. An ACK/NACK responsetransmitted in an n-th UL subframe has a relationship of an ACK/NACKresponse to DL transmission of the above three cases in an (n-k)-thsubframe(s) (where kεK and K: k₀, k₁, . . . k_(M-1) and see Table 12).Description of an ACK/NACK transmission subframe location will beomitted hereinbelow.

If ACK/NACK is transmitted from the UE through various formats,complexity of blind decoding for the BS to interpret ACK/NACK isincreased. To improve performance in the BS, such as complicated blinddecoding, and to efficiently use resources, a PUCCH format as configuredby a higher layer may be used. Hereinafter, a method of using differentTPC fields depending on whether an SPS PDSCH is present will bedescribed in detail.

When one serving cell is configured, use of a (2-bit) TPC field may bedetermined as follows. When an SPS PDSCH is present, TPC files in allPDCCHs may be used as ARIs and the UE may assume that ARI values are thesame in all PDCCHs. Meanwhile, if the SPS PDSCH is not present, a TPCfield of a PDCCH with DL DAI=1 may be used for an original TPC commandand a TPC field of a PDCCH with DL DAI>1 may be used as an ARI. The UEmay assume that ARI values are the same in all PDCCHs with DL DAI>1.

In addition, when one serving cell is configured, use of a PUCCH formatmay be determined as follows. If the UE receives ‘only’ the SPS PDSCH,LTE release-8 PUCCH format 1a/1b may be used. Alternatively, if the UEreceives ‘only’ a single PDCCH with DL DAI=1, LTE release-8 PUCCH format1a/1b may be used. In the other cases, PUCCH format 3 may be used as aPUCCH format configured by a higher layer.

If a DL DAI is used as a simple counter (PDCCH accumulation counter),resource allocation of TDD PUCCH format 3 in CA may be identical toresource allocation in a single carrier (or non-CA). That is, a resourceallocation method for a PCell may use the same method as the resourceallocation method in non-CA. In the case of CA, PUCCH resourceallocation for multiple cells may be determined as follows.

If more than one serving cell is configured, use of a TPC field may bedetermined as follows. When an SPS PDSCH is present, TPC fields of allPDCCHs on a PCell and an SCell(s) may be used for an ARI purpose and theUE may assume that ARI values on all PDCCHs on the PCell and SCell(s)are the same. Meanwhile, if the SPS PDSCH is not present, a TPC field ofa PDCCH with DL DAI=1 only on the PCell may be used for an original TPCcommand and TPC fields of all other PDCCHs on the PCell and SCell(s) maybe used for an ARI purpose. The UE may assume that ARI values on allPDCCHs on the PCell and SCell(s) are the same.

If more than one serving cell is configured, use of a PUCCH format maybe used as follows. If the UE receives ‘only’ an SPS PDSCH, LTErelease-8 PUCCH format 1a/1b may be used. Alternatively, if the UEreceives ‘only’ a single PDCCH with DL DAI=1, LTE release-8 PUCCH format1a/1b may be used. For the other cases, PUCCH format 3 may be used as aPUCCH format configured by a higher layer.

Embodiment 14

Embodiment 14 relates to a PUCCH resource allocation method for TDD HARQACK/NACK response transmission in consideration of the above-describedembodiments.

In a legacy LTE release-8/9 system, since ACK/NACK bundling (spatialbundling and/or time-domain bundling) is applied to ACK/NACKtransmission exceeding a prescribed bit size (e.g. 4 bits), loss ofindividual ACK/NACK information has been generated. In an LTE release-10(or LTE-A system) system, PUCCH format 3 is designed so as to supporttransmission of individual ACK/NACK information of up to 20 bits. In aCA and/or TDD support system, since the case in which ACK/NACK of 20bits or more is transmitted may occur, a method of efficiently usingresources while transmitting ACK/NACK information without any loss isneeded.

FIG. 45 is a diagram illustrating an example of the present inventionfor use of a TPC field in a PDCCH. In the example of FIG. 45, an ARI isinformation indicating a resource of PUCCH format 3 for ACK/NACKtransmission. Although a TPC field of a PDCCH with DL DAI=1 on a PCellis used for an original TPC command, TPC fields of the other PDCCHs onthe PCell and an SCell are used as ARIs. The UE may assume that ARIvalues on the PCell and SCell are the same. Therefore, even if only oneARI is detected, a resource of PUCCH format 3 may be determined.

When a TPC field is reused as an ARI, accuracy of PUCCH power controlmay be reduced. However, since a resource of PUCCH format 3 can becertainly determined through ARI information, transmission of ACK/NACKinformation without loss using PUCCH format 3 may be preferable foroverall system relative to reduction in accuracy of PUCCH power control.

In the example of FIG. 45, when the UE succeeds in detecting at leastone PDCCH including an ARI, an ACK/NACK response may be transmittedusing PUCCH format 3 indicated by the ARI. However, if the UE detects‘only’ a PDCCH without an ARI (i.e. a PDCCH with DAI=1 on a PCell), theUE cannot obtain ARI information and cannot determine the PUCCH format 3resource. In this case, an ACK/NACK response may be transmitted withoutinformation loss using a legacy format, i.e. PUCCH format 1a/1b of LTErelease-8/9.

Accordingly, a resource allocation method capable of transmitting anACK/NACK response to DL transmission (PDCCHs and/or PDSCHs) transmittedin one or more DL subframes without any loss may be provided. Inaddition, since a PUCCH format and a PUCCH resource are determined inthe same manner irrespective of CA or non-CA, the operations of the BSand the UE can be specified simply and clearly.

FIG. 46 is an overall flowchart explaining various embodiments proposedin the present invention. In the example of FIG. 46, a description isgiven on the premise that PUCCH format 3 is configured for the UE by ahigher layer.

In step S4610, a UE determines whether one PDSCH with DAI=1 (i.e. aPDSCH corresponding to a PDCCH with DAI=1) is received only on a PCell.

If a result of step S4610 is YES, step S4620 is performed. Since a TPCfield of the PDCCH with DAI=1 on the PCell is used for an original TPCcommand, the UE cannot acquire ARI information upon receiving only thePDCCH with DAI=1. Accordingly, the UE does not use PUCCH format 3. TheUE may transmit ACK/NACK using PUCCH format 1a/1b. A resource of PUCCHformat 1a/1b may be determined by implicit mapping (i.e. by a PUCCHresource index derived from a CCE index of the PDCCH).

Meanwhile, if the result of step S4610 is NO, step S4630 is performed.In step S4630, the UE determines whether a single PDSCH without a PDCCHonly on the PCell has been received.

If a result of step S4630 is YES, step S4640 is performed. Since the UEhas not received the PDCCH, the UE cannot acquire the ARI informationand does not use PUCCH format 3. The UE may transmit ACK/NACK usingPUCCH format 1a/1b. Here, since the PDCCH has not been received, the UEcannot derive the PUCCH resource index derived from the PDCCH CCE index.Accordingly, the UE may determine the PUCCH resource index according toinformation included in an SPS activation PDCCH (e.g. informationindicated by reuse of a TPC field in the SPS activation PDCCH).

If a result of step S4630 is NO, step S4650 is performed. In step S4650,the UE determines whether a ‘PDSCH with DAI=1’ and, additionally, ‘aPDSCH without a PDCCH’ only on the PCell have been received.

If a result of step S4650 is YES, step S4660 is performed. Even in thiscase, since the ARI information cannot be obtained, the UE uses PUCCHformat 1a/1b instead of PUCCH format 3. Here, the UE may transmitACK/NACK information by a channel selection scheme in order to preventloss of ACK/NACK information. Channel selection may be performed suchthat a PUCCH resource is selected from among A (=2 or 3) PUCCHresources. Here, a value of A may be determined according to the numberof codewords (or transport blocks) of the PDSCH.

Meanwhile, if a result of step S4650 is NO, step S4670 is performed. Instep S4670, the UE may determine whether a value of an ARI (i.e. TPCfield) of a PDCCH in which a DAI value is not 1 (i.e. DAI>1) on thePCell is equal to ARI (i.e. TPC field) values of all PDCCHs on theSCell(s).

If a result of step S4670 is YES, step S4680 is performed. In this case,the UE may transmit ACK/NACK information using a PUCCH format 3 resourceindicated by the ARI. The UE assumes that ARI values are the same in allPDCCHs and may perform step S4680 using an ARI value in at least onePDCCH.

Meanwhile, if a result of step S4670 is NO (i.e. if ARI values on thePCell and SCell(s) are not equal), the UE may discard the receivedPDCCHs.

In summary, for a ‘PDSCH with a PDCCH’, a ‘PDSCH without a PDCCH(SPS-PDSCH)’, and an ‘SPS release PDCCH’, for which the UE shouldtransmit ACK/NACK, the following UE behavior may be defined. However,the range of the present invention is not limited thereto and TDD HARQACK/NACK resource allocation and transmission operation may be performedby an available combination of various embodiments of the presentinvention.

First, operation of a non-CA system may be identical to a‘PCell-only-receiving’ operation in a CA environment. That is, the TDDHARQ ACK/NACK resource allocation and transmission operation when oneserving cell is configured for the UE may be the same as a TDD HARQACK/NACK resource allocation and transmission operation when a PDSCHand/or a PDCCH is received only on the PCell in the case where more thanone serving cell is configured. Therefore, hereinafter, description ofoperation on the PCell may be replaced with operation on a serving cellwhen only one serving cell is configured.

If a DAI in a PDCCH corresponding to a PDSCH on a PCell is 1, a TPCfield is used for an original power control purpose. If the DAI in thePDCCH corresponding to the PDSCH is greater than 1, the TPC field isused as an ARI. TPC fields in the PDCCHs corresponding to all PDSCHs onan SCell are used as ARIs. The UE assumes that all ARI values are thesame.

If the UE receives only one SPS-PDSCH only on the PCell, the UE fallsback to PUCCH format 1a/1b.

If the UE receives only one PDSCH with DAI=1 (i.e. a PDSCH with DAI=1,corresponding to PDCCH), the UE falls back to PUCCH format 1a/1b.

If one PDSCH with DAI=1 and one SPS-PDSCH are received only on thePCell, ACK/NACK transmission is performed by a channel selection schemeusing PUCCH format 1b. The number of PUCCH resources used for channelselection, A, is 2 or 3.

If one or more PDSCHs with DAI>1 (PDCCHs with DAI>1, corresponding toPDSCHs) are received, ACK/NACK transmission is performed using a PUCCHformat 3 resource indicated by an ARI.

If one or more PDSCHs are received on an SCell, ACK/NACK transmission isperformed using a PUCCH format 3 resource indicated by an ARI.

Accordingly, for all cases of receiving one of a ‘PDSCH with a PDCCH’, a‘PDSCH without a PDCCH (SPS-PDSCH)’, and an ‘SPS release PDCCH’ only ona PCell or on a PCell and an SCell(s), ACK/NACK information can becorrectly and efficiently transmitted without losing ACK/NACKinformation.

The detailed description of the preferred embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the preferred embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. Accordingly, the inventionshould not be limited to the specific embodiments described herein, butshould be accorded the broadest scope consistent with the principles andnovel features disclosed herein.

Those skilled in the art will appreciate that the present invention maybe embodied in other specific forms than those set forth herein withoutdeparting from the spirit and essential characteristics of the presentinvention. The above description is therefore to be construed in allaspects as illustrative and not restrictive. The scope of the inventionshould be determined by reasonable interpretation of the appended claimsand all changes coming within the equivalency range of the invention areintended to be within the scope of the invention. In addition, claimswhich are not explicitly dependent on each other can be combined toprovide an embodiment or new claims can be added through amendment afterthis application is filed.

INDUSTRIAL APPLICABILITY

The present invention is applicable to various mobile communicationsystems.

The invention claimed is:
 1. A method for transmittingAcknowledgement/Negative Acknowledgement (ACK/NACK) information in awireless communication system, the method performed by a User Equipment(UE) and comprising: determining a Physical Uplink Control Channel(PUCCH) format and resource through which ACK/NACK information fordownlink transmission in a downlink frame set including M (M≧1) downlinksubframes is to be transmitted; and transmitting the ACK/NACKinformation using the PUCCH format and resource in one uplink subframe,wherein more than one serving cell is configured for the UE and the morethan one serving cell includes one Primary Cell (PCell) and at least oneSecondary Cell (SCell), and wherein the ACK/NACK information istransmitted using a PUCCH format 1a/1b, when one Physical DownlinkShared Channel (PDSCH) transmission is present in the downlink subframeset only on the PCell where a corresponding Physical Downlink ControlChannel (PDCCH) is not detected, and a PDCCH indicating aSemi-Persistent Scheduling (SPS) release is not present in the downlinksubframe set.
 2. The method according to claim 1, wherein a resourceindex of the PUCCH format 1a/1b is determined by a value of a TransmitPower Control (TPC) field of a PDCCH indicating SPS activation for onePDSCH in which the corresponding PDCCH is not detected.
 3. The methodaccording to claim 1, wherein the ACK/NACK information is transmitted bychannel selection using a PUCCH format 1b, when M is greater than 1, onePDSCH transmission is present in the downlink subframe set only on thePCell where the corresponding PDCCH is not detected, a PDSCH indicatedby detection of the corresponding PDCCH in the downlink subframe set ispresent in the downlink subframe set only on the PCell, and a DownlinkAssignment Index (DAI) value of the detected PDCCH is
 1. 4. The methodaccording to claim 3, wherein the channel selection is performed byselecting one PUCCH resource from among ‘A’ PUCCH resources, wherein the‘A’ is 2 or
 3. 5. The method according to claim 4, wherein the ‘A’ isdetermined based on the number of transport blocks of the downlinktransmission.
 6. The method according to claim 4, wherein one of the ‘A’PUCCH resources is determined by a value of a TPC field of a PDCCHindicating SPS activation for the one PDSCH where the correspondingPDCCH is not detected, and the other resources of the ‘A’ PUCCHresources are derived from a Control Channel Element (CCE) index of thedetected PDCCH.
 7. The method according to claim 1, wherein a TPC fieldof a PDCCH with a DAI value being greater than 1 corresponding to aPDSCH on the PCell is used for determination of a resource index of aPUCCH format 3, and a TPC field of a PDCCH corresponding to a PDSCH oneach of the at least one SCell is used for determination of the resourceindex of the PUCCH format
 3. 8. The method according to claim 7, whereinthe UE assumes that the same PUCCH resource index value is transmittedin all PDCCHs on the PCell and the at least one SCell used fordetermination of the resource index of the PUCCH format 3 in thedownlink subframe set.
 9. The method according to claim 1, wherein thewireless communication system is a Time Division Duplex (TDD) wirelesscommunication system.
 10. A User Equipment (UE) for transmittingAcknowledgement/Negative Acknowledgement (ACK/NACK) information in awireless communication system, comprising: a reception module forreceiving a downlink signal from a Base Station (BS); a transmissionmodule for transmitting an uplink signal to the BS; and a processor forcontrolling the UE including the reception module and the transmissionmodule, wherein the processor is configured to, determine a PhysicalUplink Control Channel (PUCCH) format and resource through whichACK/NACK information for downlink transmission received through thereception module in a downlink frame set including M (M≧1) downlinksubframes is to be transmitted and transmit the ACK/NACK informationusing the PUCCH format and resource in one uplink subframe through thetransmission module, and wherein more than one serving cell isconfigured for the UE and the more than one serving cell includes onePrimary Cell (PCell) and at least one Secondary Cell (SCell), andwherein the ACK/NACK information is transmitted using a PUCCH format1a/1b, when one Physical Downlink Shared Channel (PDSCH) transmission ispresent in the downlink subframe set only on the PCell where acorresponding Physical Downlink Control Channel (PDCCH) is not detected,and a PDCCH indicating a Semi-Persistent Scheduling (SPS) release is notpresent in the downlink subframe set.
 11. The UE according to claim 10,wherein the ACK/NACK information is transmitted by channel selectionusing a PUCCH format 1b, when M is greater than 1, one PDSCHtransmission is present in the downlink subframe set only on the PCellwhere the corresponding PDCCH is not detected, a PDSCH indicated bydetection of the corresponding PDCCH is present in the downlink subframeset only on the PCell, and a Downlink Assignment Index (DAI) value ofthe detected PDCCH is
 1. 12. The UE according to claim 11, wherein thechannel selection is performed by selecting one PUCCH resource fromamong ‘A’ PUCCH resources, wherein the ‘A’ is 2 or
 3. 13. The UEaccording to claim 12, wherein the ‘A’ is determined based on the numberof transport blocks of the downlink transmission.
 14. The UE accordingto claim 12, wherein one of the ‘A’ PUCCH resources is determined by avalue of a TPC field of a PDCCH indicating SPS activation for the onePDSCH where the corresponding PDCCH is not detected and the otherresources of the ‘A’ PUCCH resources are derived from a Control ChannelElement (CCE) index of the detected PDCCH.